A126896 Numbers k such that 10*k! + 1 is prime.

0, 1, 3, 4, 5, 23, 32, 39, 61, 349, 718, 805, 1025, 1194, 1550, 1774, 3417, 7583

Offset: 1

Author

Parthasarathy Nambi, May 07 2007

Keywords

• nonn
• more

Comments

a(17) > 2880. - Jinyuan Wang, Feb 05 2020

a(19) > 12000. - Michael S. Branicky, Jul 07 2024

Examples

			k = 4 is a term because 10*4! + 1 = 241 is prime.
		

Crossrefs

Corresponding primes are in A089764.

Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A178488, A180626.

Programs

PARI

is(k) = ispseudoprime(10*k!+1); \\ Jinyuan Wang, Feb 05 2020

Extensions

a(15)-a(16) from Jinyuan Wang, Feb 05 2020

a(17) from Michael S. Branicky, Apr 16 2023

a(18) from Michael S. Branicky, Jul 07 2024