A323031 Numbers k such that 431*2^k+1 is prime.

1, 3, 9, 15, 23, 45, 47, 95, 225, 309, 363, 923, 1425, 1473, 1667, 2073, 2099, 2483, 2575, 3183, 4483, 5807, 6537, 10761, 18217, 18847, 27357, 36847, 53527, 67645, 67785, 91527, 140545, 196309, 199513, 266999, 538215, 720583, 778485, 989383, 1022695, 1315773

Offset

1,2

Comments

The associated primes are: 863, 3449, 220673, 14123009, ... - Vincenzo Librandi, Jan 06 2019

Links

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..46 (terms n = 1..44 from Robert Price)

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for 300 < k < 600

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

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Eric Weisstein's World of Mathematics, Proth Prime

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

Maple

select(k->isprime(431*2^k+1), [$1..1000]); # Muniru A Asiru, Jan 05 2019

Mathematica

Select[Range[1000], PrimeQ[431*2^# + 1] &]

Prog

(Magma) [n: n in [1..5000] | IsPrime(431*2^n+1)]; // Vincenzo Librandi, Jan 06 2019

Crossrefs

Sequence in context: A216974 A246298 A139419 * A058972 A026222 A192720

Adjacent sequences: A323028 A323029 A323030 * A323032 A323033 A323034

Keyword

nonn,hard

Author

Robert Price, Jan 05 2019

Status

approved