A358878 Numbers k such that k! + (k!/2) - 1 is prime.

2, 5, 7, 15, 20, 47, 84, 138, 169, 257, 263, 431, 559, 2939, 4403, 4870, 5273

Offset: 1

Author

Arsen Vardanyan, Dec 04 2022

Keywords

• nonn
• more

Comments

Numbers k such that A070960(k) - 1 is prime.

No more terms < 10000. - Vaclav Kotesovec, Dec 12 2022

Crossrefs

Cf. A070960, A358805.

Programs

PARI

is(k) = isprime(k!+(k!/2)-1);

Extensions

a(14)-a(17) from Vaclav Kotesovec, Dec 07 2022