[seqfan] Re: n = number of divisors of 2^n -1
Charles Greathouse
charles.greathouse at case.edu
Wed Apr 21 22:01:02 CEST 2010
Well, 32 is the last power of two in the sequence since
(2^64-1)/(2^32-1) = 641 * 6700417 is composite. Otherwise, I checked
up to 16384 without finding any members.
Charles Greathouse
Analyst/Programmer
Case Western Reserve University
On Wed, Apr 21, 2010 at 2:00 PM, Leroy Quet <q1qq2qqq3qqqq at yahoo.com> wrote:
> Oh, I see. You downloaded all of the numbers-of-divisors-of-(2^k-1)'s, and did not extend my sequence. Sorry for the confusion.
>
> Thanks,
> Leroy Quet
>
> [ ( [ ([( [ ( ([[o0Oo0Ooo0Oo(0)oO0ooO0oO0o]]) ) ] )]) ] ) ]
>
>
> --- On Wed, 4/21/10, Leroy Quet <q1qq2qqq3qqqq at yahoo.com> wrote:
>
>> From: Leroy Quet <q1qq2qqq3qqqq at yahoo.com>
>> Subject: [seqfan] Re: n = number of divisors of 2^n -1
>> To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu>
>> Date: Wednesday, April 21, 2010, 5:51 PM
>> I'm sorry. I don't know what you just
>> did.
>>
>> The number of divisors of 2^12 -1 is 24, not 12. So, 12 is
>> not in the list.
>>
>> Thanks,
>> Leroy Quet
>>
>>
>> [ ( [ ([( [ ( ([[o0Oo0Ooo0Oo(0)oO0ooO0oO0o]]) ) ] )]) ] )
>> ]
>>
>>
>> --- On Wed, 4/21/10, Richard Mathar <mathar at strw.leidenuniv.nl>
>> wrote:
>>
>> > From: Richard Mathar <mathar at strw.leidenuniv.nl>
>> > Subject: [seqfan] Re: n = number of divisors of 2^n
>> -1
>> > To: seqfan at seqfan.eu
>> > Date: Wednesday, April 21, 2010, 5:34 PM
>> >
>> > lq> From: Leroy Quet <q1qq2qqq3qqqq at yahoo.com>
>> > lq> To: seqfan at seqfan.eu
>> > lq> Subject: [seqfan] n = number of divisors of
>> > 2^n -1
>> > lq>
>> > lq> I get the sequence where a positive integer n
>> is
>> > included if
>> > lq> n = the number of divisors of 2^n - 1,
>> > lq> begins:
>> > lq> 1,2,4,6,8,16
>> >
>> > I downloaded b046801.txt and did a
>> > sort -n -k 2 b046801.txt
>> > which says that 12 is also in the list at n=21. Other
>> > members in the list are
>> >
>> > 0 1 2 4 6 8 12 16 24 32 48 64 96 128 144 160 192 256
>> 384
>> > 512 768
>> > 1024 1536 2048 3072 4096 4608 6144 8192 9216 10240
>> 12288
>> > 16384 24576
>> > 32768 49152 65536 73728 98304 131072 147456 196608
>> 262144
>> > 294912
>> > 393216 524288 655360 786432 etc
>> >
>> > but this is not necessarily a complete set, because
>> the
>> > bfile
>> > is finite.
>> >
>> >
>> > _______________________________________________
>> >
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>> >
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>>
>>
>>
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