[seqfan] Re: (3^n+1)/2 is prime, A171381
Georgi Guninski
guninski at guninski.com
Sun Jun 13 13:31:17 CEST 2010
On Sun, Jun 13, 2010 at 01:24:58AM -0400, N. J. A. Sloane wrote:
> %E A171381 Edited by N. J. A. Sloane, Dec 09 2009
> %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? (Otherwise it is awfully close to the
> powers of 2)
>
2^{15,16,17,18} are not in the sequence
user interrupt after 2h, 28mn, 32,890 ms.
(3^(2^15)+1)/2 is divisible by 2^(2^4)+1
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