

A002269


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


2



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
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OFFSET

1,2


REFERENCES

H. Riesel, "Prime numbers and computer methods for factorization," Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381384.
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..82
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), 673681.
Index entries for sequences of n such that k*2^n1 (or k*2^n+1) is prime


PROG

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


CROSSREFS

Sequence in context: A325160 A258613 A325460 * A327445 A325119 A047487
Adjacent sequences: A002266 A002267 A002268 * A002270 A002271 A002272


KEYWORD

hard,nonn


AUTHOR

N. J. A. Sloane


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 bfile, and new terms put in bfile, by Jeppe Stig Nielsen, Sep 29 2019


STATUS

approved



