A050851 Numbers k such that 199*2^k-1 is prime.

1, 5, 7, 15, 19, 23, 25, 27, 43, 65, 99, 125, 141, 165, 201, 211, 331, 369, 389, 445, 461, 463, 467, 513, 583, 835, 1071, 1085, 1107, 1187, 1197, 1491, 1513, 2505, 3859, 3941, 5989, 9693, 13125, 17009, 19459, 33147, 46433, 51091, 72813, 105169, 118531, 153127

Offset

1,2

Links

Table of n, a(n) for n=1..48.

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^n-1 (or k*2^n+1) is prime

Mathematica

Select[Range[1000], PrimeQ[199*2^# - 1] & ] (* Robert Price, Dec 29 2018 *)

Prog

(PARI) is(n)=ispseudoprime(199*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A321130 A320381 A309292 * A058918 A079360 A314365

Adjacent sequences: A050848 A050849 A050850 * A050852 A050853 A050854

Keyword

hard,nonn

Author

N. J. A. Sloane, Dec 29 1999

Extensions

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

a(48) from the Wilfrid Keller link by Robert Price, Dec 29 2018

Status

approved