A084914 Numbers k such that k^k*k! - 1 is prime.

2, 4, 30, 94, 113, 162, 296, 3243

Offset: 1

Author

Farideh Firoozbakht, Jul 14 2003

Keywords

• more
• hard
• nonn

Comments

a(1)-a(8) have been proved to correspond to primes. No other terms less than 10000. - Robert Price, May 19 2012

Examples

			4 is in the sequence because 4!*4^4 - 1 = 6143 is prime.
		

Crossrefs

Cf. A002981, A002982.

Programs

Mathematica

Do[If[PrimeQ[n^n*n!-1], Print[n]], {n, 700}]

Extensions

a(8) = 3243 from Robert Price, May 19 2012