A076681 Numbers k such that 5*k! + 1 is prime.

2, 3, 5, 10, 11, 12, 17, 34, 74, 136, 155, 259, 271, 290, 352, 479, 494, 677, 776, 862, 921, 932, 2211, 3927, 4688, 12567

Offset: 1

Author

Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 25 2002

Keywords

• nonn
• more

Comments

a(26) > 4700. - Jinyuan Wang, Feb 04 2020

Examples

			k = 3 is here because 5*3! + 1 = 31 is prime.
		

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076682, A076683, A178488, A180626, A126896.

Programs

PARI

is(k) = ispseudoprime(5*k!+1); \\ Jinyuan Wang, Feb 04 2020

Extensions

a(25) from Jinyuan Wang, Feb 04 2020

a(26) from Michael S. Branicky, Jul 03 2024