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

3, 5, 6, 9, 15, 87, 2323, 13733

Offset: 1

Author

Hugo Pfoertner, Jul 23 2019

Keywords

• nonn
• more
• hard

Comments

a(7) > 2000.

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

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

Crossrefs

Cf. A155499, A268987.

Programs

PARI

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

Extensions

a(7) from Daniel Suteu, Jul 25 2019

a(8) from Michael S. Branicky, Nov 04 2024