a(n) is never a perfect square because (2n)^(2n) is a positive square and the only squares that differ by 1 are 0 and 1. Sierpinski numbers are n^n+1. Hence this sequence is a subset of the Sierpinski numbers (A014566). - T. D. Noe, Mar 31 2006
Table of n, a(n) for n=0..10.
(PARI) forstep(x=0, 20, 2, print1(x^x+1" "))
Sequence in context: A137066 A175977 A121270 * A309675 A042341 A300900
Adjacent sequences: A085600 A085601 A085602 * A085604 A085605 A085606
Cino Hilliard, Jul 07 2003