A002269 Numbers k such that 39*2^k + 1 is prime.

1, 2, 3, 5, 7, 10, 11, 13, 14, 18, 21, 22, 31, 42, 67, 70, 71, 73, 251, 370, 375, 389, 407, 518, 818, 865, 1057, 1602, 2211, 3049, 4802, 4865, 5317, 7583, 8061, 9853, 10217, 12103, 13721, 14927, 15441, 15931, 16709, 18907, 20221, 21882, 25654, 28437, 30325

Offset: 1

Author

N. J. A. Sloane

Keywords

• hard
• nonn

References

• H. Riesel, "Prime numbers and computer methods for factorization," Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381-384.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Jeppe Stig Nielsen, Table of n, a(n) for n = 1..88
• Ray Ballinger, Proth Search Page
• Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
• Y. Gallot, Proth.exe: Windows Program for Finding Large Primes
• Wilfrid Keller, List of primes k.2^n - 1 for k < 300
• R. M. Robinson, A report on primes of the form k.2^n+1 and on factors of Fermat numbers, Proc. Amer. Math. Soc., 9 (1958), 673-681.
• Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Programs

PARI

is(n)=ispseudoprime(39*2^n+1) \\ Charles R Greathouse IV, Jun 06 2017

Extensions

Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013

a(77) from http://www.prothsearch.com/riesel1.html by Robert Price, Dec 14 2018

Terms moved from Data section to b-file, and new terms put in b-file, by Jeppe Stig Nielsen, Sep 29 2019