[seqfan] Re: (3^n+1)/2 is prime, A171381

[Max Alekseyev]

The combined results regarding GFN(3,1) are given at:
http://www1.uni-hamburg.de/RRZ/W.Keller/GFN03.html

Btw, the exponent 20 is listed there as (primality) "character unknown".
So, the claim that (3^(2^20)+1)/2 is not a prime should probably be
submitted to reflect an updated status of the exponent 20.

Btw, the corresponding comment in A093625 appears in somewhat strange
place - after a signature of Don Reble. It looks like two independent
comments were merged into a single line.

Regards,
Max

On Mon, Jun 14, 2010 at 2:09 PM, Max Alekseyev <maxale at gmail.com> wrote:
> These and some other factors are given in Björn & Riesel paper:
> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.108.8250&rep=rep1&type=pdf
> and the follow-up at
> http://www1.uni-hamburg.de/RRZ/W.Keller/GFNfacs.html
>
> Regards,
> Max
>
>
> On Mon, Jun 14, 2010 at 12:57 AM, Maximilian Hasler
> <maximilian.hasler at gmail.com> wrote:
>> On Sun, Jun 13, 2010 at 7:31 AM, Georgi Guninski <guninski at guninski.com> wrote:
>>> On Sun, Jun 13, 2010 at 01:24:58AM -0400, N. J. A. Sloane wrote:
>>>> %E A171381 Incorrect terms a(7)-a(15) deleted Jun 12 2010 by Jon Schoenfield
>>>> (or in other words, 0,1,2,4,5,6,>=15)
>>>> Can anyone find the next term?
>>>
>>> 2^{15,16,17,18} are not in the sequence
>>
>> More terms not in the sequence, because
>> (3^(2^m)+1)/2  is divisible by  1+2^(m+1)*q :
>>
>> [m,q] =
>> [3, 1]
>> [7, 1]
>> [8, 24]
>> [10, 29]
>> [11, 193]
>> [15, 1]
>> [19, 13]
>> [21, 37]
>> [26, 24]
>> [28, 23]
>> [29, 72]
>> [31, 1080]
>> [32, 24]
>> [34, 1469]
>> [36, 6630]
>> [38, 12]
>> [39, 42]
>> [44, 443]
>> [45, 228]
>> [49, 7]
>> [51, 198]
>> [54, 5]
>> [56, 2460]
>> [60, 3810]
>> [61, 18]
>> [63, 12]
>> [64, 36]
>> [72, 804]
>>
>> Maximilian
>>
>>
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