A002242 Numbers k such that 45*2^k - 1 is prime. (Formerly M0502 N0181)

1, 2, 3, 4, 5, 6, 8, 9, 14, 15, 16, 22, 28, 29, 36, 37, 54, 59, 85, 93, 117, 119, 161, 189, 193, 256, 308, 322, 327, 411, 466, 577, 591, 902, 928, 946, 1162, 1428, 1708, 1724, 2063, 2922, 2951, 3111, 3402, 4024, 4485, 5859, 6124, 8981, 10628, 19283, 23522, 26591, 28914, 33954, 34743, 76367, 103546, 103912, 104452, 125132, 139883, 174102, 249065, 306394, 368553, 528245, 645542, 818648

Offset

1,2

References

H. Riesel, Lucasian criteria for the primality of N=h.2^n-1, Math. Comp., 23 (1969), 869-875.

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..70.

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

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Kosmaj, Riesel list k<300.

Prog

(PARI) v=[ ]; for(n=1, 2000, if(isprime(45*2^n-1), v=concat(v, n), )); v

Crossrefs

Sequence in context: A121644 A259623 A305734 * A317676 A039125 A203616

Adjacent sequences: A002239 A002240 A002241 * A002243 A002244 A002245

Keyword

hard,nonn

Author

N. J. A. Sloane

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

Status

approved