OFFSET
1,2
COMMENTS
If n = 3, then 3*2^3 - 1 = 23 is prime, so 23 is not in this sequence.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..100
EXAMPLE
a(1) = 1 = 2*1^2 - 1.
a(2) = 323 = 4*3^4 - 1.
MATHEMATICA
Select[Table[n (n - 1)^n - 1, {n, 2, 20}], ! PrimeQ[#] &] (* Vincenzo Librandi, Mar 22 2014 *)
PROG
(Magma) [a: n in [2..40] | not IsPrime(a) where a is n*(n-1)^n-1]; // Vincenzo Librandi, Jun 13 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Jun 13 2011
EXTENSIONS
Corrected and extended by Vincenzo Librandi, Jun 13 2011
STATUS
approved