A050837 Numbers k such that 171*2^k-1 is prime.

2, 3, 5, 10, 25, 29, 39, 73, 103, 109, 123, 198, 378, 434, 825, 925, 1265, 1802, 2134, 2199, 2629, 3154, 3490, 4093, 4814, 5490, 7029, 9074, 9298, 10249, 10505, 12185, 16382, 19030, 26237, 28890, 40123, 61483, 129309, 133527, 182745, 259262, 269539, 290403, 576733, 590818, 684003

Offset

1,1

Links

Table of n, a(n) for n=1..47.

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[171*2^# - 1] & ] (* Robert Price, Dec 29 2018 *)

Prog

(PARI) is(n)=ispseudoprime(171*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A155587 A125658 A001200 * A107578 A011827 A260304

Adjacent sequences: A050834 A050835 A050836 * A050838 A050839 A050840

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(44)-a(47) from the Wilfrid Keller link by Robert Price, Dec 29 2018

Status

approved