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 A002259 Numbers k such that 17*2^k + 1 is prime. (Formerly M2985 N1206) 2
 3, 15, 27, 51, 147, 243, 267, 347, 471, 747, 2163, 3087, 5355, 6539, 7311, 99231, 824451, 1388355, 1990299 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 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 Table of n, a(n) for n=1..19. 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 PROG (PARI) is(n)=ispseudoprime(17*2^n+1) \\ Charles R Greathouse IV, Jun 06 2017 CROSSREFS Sequence in context: A017557 A147041 A347536 * A050848 A077785 A222291 Adjacent sequences: A002256 A002257 A002258 * A002260 A002261 A002262 KEYWORD hard,more,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 STATUS approved

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Last modified May 27 00:17 EDT 2024. Contains 372847 sequences. (Running on oeis4.)