A191715 Nonprime numbers of the form n*(n-1)^n - (n-1)*n^(n-1) + 1.

1, 133, 54871, 1253659, 31438345, 863585785, 25867844011, 840625753991, 29488048443085, 1111334648458165, 44804977347486175, 1924820469011714611, 87800711122303545361, 4238935318038328143857, 11582179256389013503203871, 652184749150919163867112021

Offset

1,2

Comments

If n=3, then 3*2^3-2*3^2+1=7 is prime, so 7 is not in this sequence. If n=5, then 5*4^5-4*5^4+1=2621 is prime.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..377

Mathematica

Union[Select[Table[n(n-1)^n-(n-1)n^(n-1)+1, {n, 30}], !PrimeQ[#]&]] (* Harvey P. Dale, Jun 19 2011 *)

Prog

(Magma) [ a: n in [2..40] | not IsPrime(a) where a is n*(n-1)^n-(n-1)*n^(n-1)+1 ]; // Vincenzo Librandi, Jun 13 2011
(PARI) for(n=1, 1e3, if(!ispseudoprime(k=n*(n-1)^n-(n-1)*n^(n-1)+1), print1(k", ")))

Crossrefs

Cf. A191409, A191699.

Sequence in context: A281496 A015264 A055579 * A208626 A061491 A274132

Adjacent sequences: A191712 A191713 A191714 * A191716 A191717 A191718

Keyword

nonn

Author

Juri-Stepan Gerasimov, Jun 12 2011

Status

approved