From: Maximilian Hasler <maximilian.hasler(AT)gmail.com>
Date: Mon, 14 Jun 2010 00:57:08 -0400
Subject: Re: [seqfan] Re: (3^n+1)/2 is prime, A171381

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

Date: Mon, 14 Jun 2010 14:06:59 +0300
From: Georgi Guninski <guninski(AT)guninski.com>

some more not in the sequence:

72 <= m <= 200, q <= 2*10^6
m  q
72 804 
73 1947709 
79 18 
80 11 
82 235134 
91 235 
94 4482 
95 2263 
100 328541 
123 163 
125 1354704 
126 5 
128 100290 
139 31 
155 11670 
158 72 
161 150 
186 326129 
187 6 
198 12 
199 427