A309140 Numbers k such that k^(k + 1) + k - 1 is prime.

3, 5, 6, 9, 15, 87, 2323

Offset

1,1

Comments

a(7) > 2000.

a(8) > 5000. - Daniel Suteu, Jul 25 2019

a(8) > 10000. - Michael S. Branicky, Apr 01 2023

Links

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

Prog

(PARI) for(n=1, 100, my(x=n^(n+1)+n-1); if(isprime(x), print1(n, ", ")))

Crossrefs

Cf. A155499, A268987.

Sequence in context: A070117 A176345 A101139 * A102606 A102372 A095829

Adjacent sequences: A309137 A309138 A309139 * A309141 A309142 A309143

Keyword

nonn,more,hard

Author

Hugo Pfoertner, Jul 23 2019

Extensions

a(7) from Daniel Suteu, Jul 25 2019

Status

approved