[seqfan] Re: SeqFan Digest, Vol 50, Issue 4

Antti Karttunen antti.karttunen at gmail.com
Sun Nov 18 00:45:57 CET 2012


On Sat, Nov 17, 2012 at 9:08 PM,  <seqfan-request at list.seqfan.eu> wrote:
>

> Message: 8
> Date: Fri, 16 Nov 2012 11:44:34 -0800 (PST)
> From: Tom Duff <td at pixar.com>
> To: seqfan at list.seqfan.eu
> Subject: [seqfan] Re: Excessive b-file, perhaps?
> Message-ID:
>         <alpine.LRH.2.02.1211161122030.2688 at marvin.dynamic.pixar.com>
> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
>
> Quoth David Wilson <davidwwilson at comcast.net>:
>
>> Perhaps A000959 has an unduly large b-file (200K terms).  It bogs the
>> graph, and even downloading the b-file is noticeably slower than
>> instantaneous.
>>
>> I don't mind having the file around, but aren't 10K terms sufficient for
>> a b-file?
>
> It is obviously useful to have as many terms for each sequence as we can
> afford to store.  The b file for A000959 is only 2.8 MB.  If the average
> b-file were that long, it would only take about 600 GB to store them all.
> Certainly it would be useful to return shorter results to casual users
> (including the graphs.)

I second that, especially if the terms are not trivial to compute. And
in any case, if the user is so interested about a particular sequence
that wants to even load its b-file, then maybe (s)he has then also
patience to wait for longer than just an instantaneous moment?

>
> A reasonable compromise might be for the server to only give you the first
> few thousand terms if you ask to see http://oeis.org/b000959.txt but have
> other means to get the whole thing. http://oeis.org/b000959.txt?all might
> be an idea.  I am uninterested in the particular syntax, but you could,
> for example allow asking for ranges of terms:
> http://oeis.org/b000959.txt?10000-1000000 and even other, more complex
> queries.  Depends on how much the person that implements it is up for.
>
> While we're asking for implausible features, I would love to be able to
> get a bulk download of all the b files for exploratory work. (Maybe
> there's an easy way to do that already and I just don't know about it.  I
> can certainly write a short shell script that does the job, though I would
> be loath to beat on the server that hard.)

I would like that also. Soon having a big machine needing a lots of
test-data for a graph database. Storing all the OEIS-sequences term by
term, and then looking for easy conjectures/connections might yield
something useful for SeqFans as well?

Is it OK for OEIS administrators if one loads the b-files with some
wget-script that keeps enough pause between downloads, as to avoid
overloading the server?

BTW, I wonder which sequences will be starring in the next Pixar movie? ;-)

Yours,

Antti Karttunen

>
> --
> Tom Duff.  Two red 10' stepladders used to be behind the Castle.
>
>
> ------------------------------
>
> Message: 9
> Date: Sat, 17 Nov 2012 08:59:25 +0200
> From: Georgi Guninski <guninski at guninski.com>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Subject: [seqfan] Re: Fixing A175155 Numbers n satisfying n^2 + 1 =
>         x^2 y^3
> Message-ID: <20121117065925.GA2534 at sivokote.iziade.m$>
> Content-Type: text/plain; charset=us-ascii
>
> Robert,
>
> You submitted a b-file. Are you sure you are not missing terms?
>
> Is it possible for large k
> x^2 - k^3 y^2 = -1
> to have relatively small solution x?
> (Probably this depends on the length of the period of the c.f.).
>
>
>
> On Fri, Nov 16, 2012 at 12:54:17PM -0500, Robert G. Wilson v wrote:
>> SeqFans,
>>
>>       Here is what I get so far.
>>
>>   682
>>   1268860318
>>   1459639851109444
>>   2360712083917682
>>   4392100110703410665318
>>   8171493471761113423918890682
>>   15203047261220215902863544865414318
>>   28285239023397517753374058381589688919682
>>   12439333951782387734360136352377558500557329868
>>   52624630632537831937855708654927989510825107318
>>   97908020042547086005693272723322840570529500826004682
>>   182157675473066143788787784683258842527134067238269233744318
>>   338903990902190706366709548741628016731324554988094903342010145682
>>   630530197265361847138377315870912654087912613063713457410764922787325318
>>
>> 1060104169164423772274446059994682269961159864044458330444625185013342888064
>> 84
>>   ...
>>
>> 4279104078004899022080917697403989475430634859934233351021743853386879637099
>> 3207437700222532927350542021925898943115140846846046603791372889127160448480
>> 6456648567809059292918190921243953601798103132062280668429245895045322132474
>> 8652845281679499196042278242733025358631331870513056058535101653128688454846
>> 1633431386777413294481337916503669521364720759917056738645910768971999734826
>> 6905616
>>
>> Sincerely yours, Bob.
>>
>
>
> ------------------------------
>
> Message: 10
> Date: Sat, 17 Nov 2012 12:02:18 +0200
> From: Georgi Guninski <guninski at guninski.com>
> To: seqfan at list.seqfan.eu
> Subject: [seqfan] Software for searching for Wolstenholme primes?
> Message-ID: <20121117100218.GB2534 at sivokote.iziade.m$>
> Content-Type: text/plain; charset=us-ascii
>
> Out of blind opportunism I am looking for efficient software for
> verifying if a prime is a  Wolstenholme prime A088164.
>
> The basic definition requires computing a binomial coefficient
> mod p^4.
>
> For this task found Max Alekseyev's pari binomod.gp, but it appears
> slow to me: for p=2124679 binomod took 6 seconds.
>
> Is there efficient software or references for searching
> for Wolstenholme primes?
>
>
> ------------------------------
>
> Message: 11
> Date: Sat, 17 Nov 2012 06:26:32 -0500
> From: Hans Havermann <gladhobo at teksavvy.com>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Subject: [seqfan] Re: Software for searching for Wolstenholme primes?
> Message-ID: <0101D039-B99C-4298-ABA6-0C6A64BCC642 at teksavvy.com>
> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>
> Georgi Guninski:
>
>> Is there efficient software or references for searching for
>> Wolstenholme primes?
>
> Ronald Bruck has a page devoted to this:
>
> http://imperator.usc.edu/~bruck/research/stirling/
>
>
> ------------------------------
>
> Message: 12
> Date: Sat, 17 Nov 2012 14:06:39 +0200
> From: Georgi Guninski <guninski at guninski.com>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Subject: [seqfan] Re: Software for searching for Wolstenholme primes?
> Message-ID: <20121117120639.GC2534 at sivokote.iziade.m$>
> Content-Type: text/plain; charset=us-ascii
>
> On Sat, Nov 17, 2012 at 06:26:32AM -0500, Hans Havermann wrote:
>> Georgi Guninski:
>>
>> >Is there efficient software or references for searching for
>> >Wolstenholme primes?
>>
>> Ronald Bruck has a page devoted to this:
>>
>> http://imperator.usc.edu/~bruck/research/stirling/
>>
>
> Thanks. The problem might not be very fast:
>
> time ./gmpstirling 100000007
> 100000007       5973868118170739         20.497
>
> real    0m20.497s
> user    0m20.500s
>
>
> Max's pari:
> ? ##
>   ***   last result computed in 4min, 39,350 ms.
>
>
> ------------------------------
>
> Message: 13
> Date: Sat, 17 Nov 2012 08:04:58 -0500
> From: Neil Sloane <njasloane at gmail.com>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Subject: [seqfan] Re: Fixing A175155 Numbers n satisfying n^2 + 1 =
>         x^2 y^3
> Message-ID:
>         <CAAOnSgTyq=8BAdHw8uzv_Xhy6j6EsmZWmrYUQv=4MS1qYqhxWg at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> I agree that 0 should be in the sequence. I added it and added the
> condition that x and y should be positive. The b-file is now wrong, since 0
> is missing, but I assume Bob Wilson will be changing it anyway when he
> responds to Georgi's comment.
> Neil
>
> On Sat, Nov 17, 2012 at 1:59 AM, Georgi Guninski <guninski at guninski.com>wrote:
>
>> Robert,
>>
>> You submitted a b-file. Are you sure you are not missing terms?
>>
>> Is it possible for large k
>> x^2 - k^3 y^2 = -1
>> to have relatively small solution x?
>> (Probably this depends on the length of the period of the c.f.).
>>
>>
>>
>> On Fri, Nov 16, 2012 at 12:54:17PM -0500, Robert G. Wilson v wrote:
>> > SeqFans,
>> >
>> >       Here is what I get so far.
>> >
>> >   682
>> >   1268860318
>> >   1459639851109444
>> >   2360712083917682
>> >   4392100110703410665318
>> >   8171493471761113423918890682
>> >   15203047261220215902863544865414318
>> >   28285239023397517753374058381589688919682
>> >   12439333951782387734360136352377558500557329868
>> >   52624630632537831937855708654927989510825107318
>> >   97908020042547086005693272723322840570529500826004682
>> >   182157675473066143788787784683258842527134067238269233744318
>> >   338903990902190706366709548741628016731324554988094903342010145682
>> >
>> 630530197265361847138377315870912654087912613063713457410764922787325318
>> >
>> >
>> 1060104169164423772274446059994682269961159864044458330444625185013342888064
>> > 84
>> >   ...
>> >
>> >
>> 4279104078004899022080917697403989475430634859934233351021743853386879637099
>> >
>> 3207437700222532927350542021925898943115140846846046603791372889127160448480
>> >
>> 6456648567809059292918190921243953601798103132062280668429245895045322132474
>> >
>> 8652845281679499196042278242733025358631331870513056058535101653128688454846
>> >
>> 1633431386777413294481337916503669521364720759917056738645910768971999734826
>> > 6905616
>> >
>> > Sincerely yours, Bob.
>> >
>>
>> _______________________________________________
>>
>> Seqfan Mailing list - http://list.seqfan.eu/
>>
>
>
>
> --
> Dear Friends, I have now retired from AT&T. New coordinates:
>
> Neil J. A. Sloane, President, OEIS Foundation
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
> ------------------------------
>
> Message: 14
> Date: Sat, 17 Nov 2012 17:17:48 +0200
> From: Georgi Guninski <guninski at guninski.com>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Subject: [seqfan] Re: Fixing A175155 Numbers n satisfying n^2 + 1 =
>         x^2 y^3
> Message-ID: <20121117151748.GD2534 at sivokote.iziade.m$>
> Content-Type: text/plain; charset=us-ascii
>
> On Sat, Nov 17, 2012 at 08:04:58AM -0500, Neil Sloane wrote:
>> I agree that 0 should be in the sequence. I added it and added the
>> condition that x and y should be positive. The b-file is now wrong, since 0
>> is missing, but I assume Bob Wilson will be changing it anyway when he
>> responds to Georgi's comment.
>> Neil
>>
>
> I wonder if there is some identity to generate terms from
> known ones without Pell equations.
>
> Generating powerfull solutions to x^2-1,x^2 is via a simple map
> described in A060355.
>
> Is there a powerful polynomial F(x) s.t. F(x) (x^2+1) - 1 = G(x)^2?
>
>
> ------------------------------
>
> Message: 15
> Date: Sat, 17 Nov 2012 14:08:47 -0500
> From: "Robert G. Wilson v" <rgwv at rgwv.com>
> To: "'Sequence Fanatics Discussion list'" <seqfan at list.seqfan.eu>
> Subject: [seqfan] Re: Fixing A175155 Numbers n satisfying n^2 + 1 =
>         x^2 y^3
> Message-ID: <013601cdc4f6$f918e690$eb4ab3b0$@com>
> Content-Type: text/plain;       charset="us-ascii"
>
> Consider it done. Bob.
>
> -----Original Message-----
> From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Neil Sloane
> Sent: Saturday, November 17, 2012 8:05 AM
> To: Sequence Fanatics Discussion list
> Subject: [seqfan] Re: Fixing A175155 Numbers n satisfying n^2 + 1 = x^2 y^3
>
> I agree that 0 should be in the sequence. I added it and added the condition
> that x and y should be positive. The b-file is now wrong, since 0 is
> missing, but I assume Bob Wilson will be changing it anyway when he responds
> to Georgi's comment.
> Neil
>
> On Sat, Nov 17, 2012 at 1:59 AM, Georgi Guninski
> <guninski at guninski.com>wrote:
>
>> Robert,
>>
>> You submitted a b-file. Are you sure you are not missing terms?
>>
>> Is it possible for large k
>> x^2 - k^3 y^2 = -1
>> to have relatively small solution x?
>> (Probably this depends on the length of the period of the c.f.).
>>
>>
>>
>> On Fri, Nov 16, 2012 at 12:54:17PM -0500, Robert G. Wilson v wrote:
>> > SeqFans,
>> >
>> >       Here is what I get so far.
>> >
>> >   682
>> >   1268860318
>> >   1459639851109444
>> >   2360712083917682
>> >   4392100110703410665318
>> >   8171493471761113423918890682
>> >   15203047261220215902863544865414318
>> >   28285239023397517753374058381589688919682
>> >   12439333951782387734360136352377558500557329868
>> >   52624630632537831937855708654927989510825107318
>> >   97908020042547086005693272723322840570529500826004682
>> >   182157675473066143788787784683258842527134067238269233744318
>> >   338903990902190706366709548741628016731324554988094903342010145682
>> >
>> 6305301972653618471383773158709126540879126130637134574107649227873253
>> 18
>> >
>> >
>> 1060104169164423772274446059994682269961159864044458330444625185013342
>> 888064
>> > 84
>> >   ...
>> >
>> >
>> 4279104078004899022080917697403989475430634859934233351021743853386879
>> 637099
>> >
>> 3207437700222532927350542021925898943115140846846046603791372889127160
>> 448480
>> >
>> 6456648567809059292918190921243953601798103132062280668429245895045322
>> 132474
>> >
>> 8652845281679499196042278242733025358631331870513056058535101653128688
>> 454846
>> >
>> 1633431386777413294481337916503669521364720759917056738645910768971999
>> 734826
>> > 6905616
>> >
>> > Sincerely yours, Bob.
>> >
>>
>> _______________________________________________
>>
>> Seqfan Mailing list - http://list.seqfan.eu/
>>
>
>
>
> --
> Dear Friends, I have now retired from AT&T. New coordinates:
>
> Neil J. A. Sloane, President, OEIS Foundation
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> SeqFan mailing list
> SeqFan at list.seqfan.eu
> http://list.seqfan.eu/cgi-bin/mailman/listinfo/seqfan
>
> ------------------------------
>
> End of SeqFan Digest, Vol 50, Issue 4
> *************************************


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