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A002258 Numbers k such that 15*2^k + 1 is prime.
(Formerly M1165 N0445)
3
1, 2, 4, 9, 10, 12, 27, 37, 38, 44, 48, 78, 112, 168, 229, 297, 339, 517, 522, 654, 900, 1518, 2808, 2875, 3128, 3888, 4410, 6804, 7050, 7392, 19219, 21445, 21550, 24105, 24995, 34224, 34260, 43388, 48444, 61758, 184290, 294894, 300488, 403929, 483098, 635989 (list; graph; refs; listen; history; text; internal format)
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. 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..61
Ray Ballinger, Proth Search Page
Ray Ballinger and 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.
MATHEMATICA
Select[Range[1000], PrimeQ[15*2^#+1] &] (* Amiram Eldar, Dec 12 2018 *)
PROG
(PARI) for(n=1, 10^10, if(ispseudoprime(15<<n+1), print1(n, ", "))); \\ Joerg Arndt, Feb 23 2014
CROSSREFS
Sequence in context: A226821 A047465 A365343 * A252760 A191766 A287518
KEYWORD
hard,nonn
AUTHOR
EXTENSIONS
Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013
a(57)-a(60) from http://www.prothsearch.com/riesel1.html by Robert Price, Dec 12 2018
Terms moved from Data to b-file, and one new term put in b-file, by Jeppe Stig Nielsen, Oct 16 2019
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)