A294722 Numbers k such that (44^k - 1)/43 is prime.

5, 31, 167, 100511

Offset: 1

Author

Paul Bourdelais, Nov 07 2017

Keywords

• nonn
• more

Comments

The number corresponding to a(4) is a probable prime.

These are the indices of base-44 repunit primes, i.e., numbers k such that A002275(k) interpreted as a base-44 number and converted to decimal is prime. - Felix Fröhlich, Nov 08 2017

Links

• P. Bourdelais, A generalized repunit conjecture

Crossrefs

Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035, A127995, A127996, A127997, A127998, A127999, A098438, A128002, A128003, A128004, A128005, A240765.

Programs

Mathematica

ParallelMap[ If[ PrimeQ[(44^# - 1)/43], #, Nothing] &, Prime@Range @ 10000] (* Robert G. Wilson v, Nov 25 2017 *)

PARI

is(n) = ispseudoprime((44^n-1)/43) \\ Felix Fröhlich, Nov 08 2017

PFGW

ABC2 (44^$a-1)/43 // -f{2*$a}
a: primes from 2 to 1000000