A191717 Numbers n such that n*(n-1)^n-(n-1)*n^(n-1)+1 is prime.

3, 5, 18, 23, 78, 131, 177

Offset

1,1

Links

Table of n, a(n) for n=1..7.

Example

a(1)=3 because 3*2^3-2*3^2+1=7 is prime, a(2)=5 because 5*4^5-4*5^4+1=2621 is prime.

Prog

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

Crossrefs

Cf. A191699, A191715.

Sequence in context: A249759 A358342 A039584 * A136131 A143546 A069066

Adjacent sequences: A191714 A191715 A191716 * A191718 A191719 A191720

Keyword

nonn,hard

Author

Juri-Stepan Gerasimov, Jun 12 2011

Status

approved