A049432 Numbers k such that k! - (k-1)! + 1 is prime.

2, 3, 4, 5, 6, 8, 13, 20, 24, 46, 59, 150, 152, 198, 683, 880, 1135, 1907, 6617, 10243, 12016

Offset: 1

Author

Paul Jobling (paul.jobling(AT)whitecross.com)

Keywords

• nonn

Comments

a(21) > 12000. [From Donovan Johnson, Dec 18 2009]

Examples

			6! - (6-1)! + 1 = 601 is prime.
		

Links

• Index entries for sequences related to factorial numbers

Crossrefs

Cf. A049984, A049433, A090703.

Formula

a(n) = A090703(n) + 1. - Michael S. Branicky, Jun 11 2025

Extensions

a(15)-a(16) from Farideh Firoozbakht, Jul 18 2003

a(17)-a(20) from Donovan Johnson, Dec 18 2009

a(21) from Michael S. Branicky, Jun 11 2025