A032421 Numbers k such that 143*2^k+1 is prime.

53, 77, 293, 333, 393, 809, 825, 20973, 85349, 270285, 459093, 699189, 859769, 1650689

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

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

Mathematica

Select[Range[1000], PrimeQ[143*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

Prog

(PARI) is(n)=ispseudoprime(143*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A039389 A043212 A043992 * A129257 A125875 A059245

Adjacent sequences: A032418 A032419 A032420 * A032422 A032423 A032424

Keyword

nonn,hard,more

Author

James R. Buddenhagen

Extensions

a(10)-a(14) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

Status

approved