A316712 Numbers k such that 421*2^k+1 is prime.

4, 8, 12, 16, 24, 36, 72, 196, 576, 928, 3336, 5172, 5996, 6196, 13204, 28484, 36984, 43740, 58744, 62244, 112876, 127852, 143208, 170612, 174372, 221372, 350356, 832528, 1070460, 1729092, 2539336, 3905144

Offset

1,1

Links

Table of n, a(n) for n=1..32.

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(421*2^k+1), [$1..1000]); # Muniru A Asiru, Jan 05 2019

Mathematica

Select[Range[1000], PrimeQ[421*2^# + 1] &]

Crossrefs

Sequence in context: A291834 A291928 A045783 * A261650 A178731 A334386

Adjacent sequences: A316709 A316710 A316711 * A316713 A316714 A316715

Keyword

nonn,more,hard

Author

Robert Price, Jan 04 2019

Extensions

a(31) from Jeppe Stig Nielsen, Jan 04 2020

a(32) from Jeppe Stig Nielsen, Dec 18 2024

Status

approved