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A191715 Nonprime numbers of the form n*(n-1)^n - (n-1)*n^(n-1) + 1. 3
1, 133, 54871, 1253659, 31438345, 863585785, 25867844011, 840625753991, 29488048443085, 1111334648458165, 44804977347486175, 1924820469011714611, 87800711122303545361, 4238935318038328143857, 11582179256389013503203871, 652184749150919163867112021 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 19 13:00 EDT 2021. Contains 343114 sequences. (Running on oeis4.)