A308553 Numbers k such that 5^(k+3) + 3^(k+2) + 2^(k+1) + 1 is prime.

0, 4, 8, 524, 972, 3780, 7704

Offset

1,2

Comments

Larger k values yield probable primes.

a(8) > 50000 (if it exists).

Links

Table of n, a(n) for n=1..7.

Mathematica

ParallelTable[If[PrimeQ[5^(n+3) + 3^(n+2) + 2^(n+1) + 1], n, Nothing], {n, 0, 10^4}]

Crossrefs

Cf. A306573.

Sequence in context: A012994 A136386 A260726 * A177860 A013443 A013442

Adjacent sequences: A308550 A308551 A308552 * A308554 A308555 A308556

Keyword

nonn,hard,more

Author

Mikk Heidemaa, Jun 07 2019

Status

approved