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Numbers k such that 39*2^k + 1 is prime.
(Formerly M0640 N0234)
2

%I M0640 N0234 #52 Aug 30 2020 02:30:16

%S 1,2,3,5,7,10,11,13,14,18,21,22,31,42,67,70,71,73,251,370,375,389,407,

%T 518,818,865,1057,1602,2211,3049,4802,4865,5317,7583,8061,9853,10217,

%U 12103,13721,14927,15441,15931,16709,18907,20221,21882,25654,28437,30325

%N Numbers k such that 39*2^k + 1 is prime.

%D H. Riesel, "Prime numbers and computer methods for factorization," Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381-384.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Jeppe Stig Nielsen, <a href="/A002269/b002269.txt">Table of n, a(n) for n = 1..84</a>

%H Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a>

%H Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/riesel1.html">List of primes k.2^n + 1 for k < 300</a>

%H Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a>

%H Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a>

%H R. M. Robinson, <a href="https://doi.org/10.1090/S0002-9939-1958-0096614-7">A report on primes of the form k.2^n+1 and on factors of Fermat numbers</a>, Proc. Amer. Math. Soc., 9 (1958), 673-681.

%H <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a>

%o (PARI) is(n)=ispseudoprime(39*2^n+1) \\ _Charles R Greathouse IV_, Jun 06 2017

%K hard,nonn

%O 1,2

%A _N. J. A. Sloane_

%E Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013

%E a(77) from http://www.prothsearch.com/riesel1.html by _Robert Price_, Dec 14 2018

%E Terms moved from Data section to b-file, and new terms put in b-file, by _Jeppe Stig Nielsen_, Sep 29 2019