A191568 Numbers k such that k*(k+1)^k+1 is prime.

1, 2, 3, 9, 10, 14, 33, 36

Offset: 1

Author

Juri-Stepan Gerasimov, Jun 13 2011

Keywords

• nonn
• hard
• more

Comments

The corresponding primes are a subset of the generalized Cullen primes (A210339 U A050920). - Jeppe Stig Nielsen, Apr 12 2016

Examples

			a(1)=1 because 1*2^1+1=3 is prime, a(2)=2 because 2*3^2+1=19 is prime, a(3)=3 because 3*4^3+1=193 is prime, a(4)=9 because 9*10^9+1=9000000001 is prime, a(5)=10 because 10*11^10+1=259374246011 is prime.
		

Crossrefs

Cf. A109618, A110709, A210339, A271718.

Programs

Mathematica

Select[Range@ 100, PrimeQ[# (# + 1)^# + 1] &] (* Michael De Vlieger, Apr 12 2016 *)

PARI

is(n)=ispseudoprime(n*(n+1)^n+1) \\ Charles R Greathouse IV, Jun 13 2017