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A002237
Numbers k such that 15*2^k - 1 is prime.
(Formerly M0976 N0365)
3
1, 2, 4, 5, 10, 14, 17, 31, 41, 73, 80, 82, 116, 125, 145, 157, 172, 202, 224, 266, 289, 293, 463, 1004, 1246, 2066, 2431, 2705, 4622, 5270, 7613, 21727, 21962, 40742, 41054, 60622, 83263, 83669, 91457, 103940, 104177, 108124, 115327, 161453, 172714, 454681, 568780, 656264, 712294, 902474, 1084010, 1344313
OFFSET
1,2
COMMENTS
The results were partially computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019
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).
PROG
(PARI) for(n=1, 10^10, if(ispseudoprime(15<<n-1), print1(n, ", "))); \\ Joerg Arndt, Feb 23 2014
CROSSREFS
Cf. A002258: 15*2^n+1 is prime.
Sequence in context: A264855 A154318 A008283 * A329136 A067935 A228893
KEYWORD
hard,nonn
EXTENSIONS
More terms from Hugo Pfoertner, Jun 29 2004
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
STATUS
approved