[seqfan] Re: A046452
Robert G. Wilson v
rgwv at rgwv.com
Fri Jan 4 23:12:21 CET 2013
Harvey,
I agree now that you are correct.
Here is the Mmca: fQ[n_] :=
Block[{t = Table[#[[1]], {#[[2]]}] & /@ FactorInteger[n]}, tt = Flatten@
IntegerDigits@ t; Length@ Flatten@ t == 3 && tt == Reverse@ tt];
Select[Range at 30000, fQ]
And it produces:
{8, 27, 125, 343, 429, 507, 795, 1309, 1331, 1533, 1547, 1587, 2023, 2097,
3633, 3729, 3897, 5289, 5295, 5547, 6597, 7833, 8029, 8427, 9583, 9795,
12207, 12795, 13489, 13573, 14133, 14147, 14295, 15463, 15549, 15987, 16233,
17295, 20667, 22139, 28273, 28609, 28847, 28951, 29729, 29829}
Bob.
-----Original Message-----
From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Harvey P.
Dale
Sent: Friday, January 04, 2013 3:17 PM
To: Sequence Fanatics Discussion list
Subject: [seqfan] Re: A046452
Graeme:
Then would this definition work: "Numbers n with three prime factors
such that the concatenation of those prime factors is a palindrome"?
And why are the numbers I mentioned in my earlier email (below) not
in the current sequence?
Best,
Harvey
-----Original Message-----
From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Graeme
McRae
Sent: Friday, January 04, 2013 3:04 PM
To: Sequence Fanatics Discussion list
Subject: [seqfan] Re: A046452
Because the elements a(n) of sequence A046452 have nothing to do with n.
It's just a list of numbers, a(n), satisfying the property. I agree with
you, though, that the word "composite" is superfluous.
--Graeme McRae
Palmdale, CA
On Fri, Jan 4, 2013 at 11:58 AM, Harvey P. Dale <hpd at hpdale.org> wrote:
> I believe I am misunderstanding something about the above
> sequence. Why aren't these numbers in the sequence: 3729, 28609,
> 28847, 28951, 29729, 29829? And why does the definition read,
> "Concatenation of the 3 prime factors of composite a(n) is a
> palindrome," rather than "Concatenation of the 3 prime factors of n is a
palindrome"?
> Clarification would be appreciated.
> Best,
> Harvey
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>
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