

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
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

The results were partially computed using the PrimeFormGW (PFGW) primalitytesting 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. 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

Table of n, a(n) for n=1..52.
Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
Wilfrid Keller, List of primes k.2^n  1 for k < 300
Kosmaj, Riesel list k<300. Index entries for sequences of n such that k*2^n1 (or k*2^n+1) is prime
H. Riesel, Lucasian criteria for the primality of N=h.2^n1, Math. Comp., 23 (1969), 869875.
Index entries for sequences of n such that k*2^n1 (or k*2^n+1) is prime


PROG

(PARI) for(n=1, 10^10, if(ispseudoprime(15<<n1), 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
Adjacent sequences: A002234 A002235 A002236 * A002238 A002239 A002240


KEYWORD

hard,nonn


AUTHOR

N. J. A. Sloane, Simon Plouffe


EXTENSIONS

More terms from Hugo Pfoertner, Jun 29 2004
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008


STATUS

approved



