A085602 Numbers of the form (2n+1)^(2n+1) + 1.

2, 28, 3126, 823544, 387420490, 285311670612, 302875106592254, 437893890380859376, 827240261886336764178, 1978419655660313589123980, 5842587018385982521381124422, 20880467999847912034355032910568, 88817841970012523233890533447265626

Offset

1,1

Comments

Also even Sierpinski numbers of the first kind.

No term is a square. Moreover, x^x + 1 != k^x, for if it were, we would have a counterexample to Fermat's Last Theorem.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..193

Formula

a(n) = (2*n-1)^(2*n-1)+1. - Alois P. Heinz, Feb 27 2020

Mathematica

#^#+1&/@Range[1, 21, 2] (* Harvey P. Dale, Dec 08 2012 *)

Prog

(PARI) forstep(x=1, 20, 2, print1(x^x+1" "))

Crossrefs

Bisection of A014566 (odd part).

Sequence in context: A230700 A168554 A152792 * A058502 A080266 A308757

Adjacent sequences: A085599 A085600 A085601 * A085603 A085604 A085605

Keyword

easy,nonn

Author

Cino Hilliard, Jul 07 2003

Status

approved