A366820 a(n) is the sum of the divisors of n^n + 1.

3, 3, 6, 56, 258, 6264, 52136, 1559520, 17041416, 706911048, 10102223208, 706019328000, 9101898907920, 519285252355776, 11672709747324912, 880565163670372352, 18446811354131136516, 1792353900753729655758, 54357680125881245248800, 4154723599066412190910560

Offset

0,1

Links

Table of n, a(n) for n=0..19.

Eric Weisstein's World of Mathematics, Sierpinski Number of the First Kind

Formula

a(n) = A000203(A014566(n)).

Mathematica

{3}~Join~Array[DivisorSigma[1, #^# + 1] &, 19] (* Michael De Vlieger, Oct 24 2023 *)

Prog

(PARI) a(n) = sigma(n^n+1);

Crossrefs

Cf. A000203, A007571, A014566, A055385, A062727, A344859, A366819.

Sequence in context: A221886 A221925 A221688 * A066358 A261295 A118031

Adjacent sequences: A366817 A366818 A366819 * A366821 A366822 A366823

Keyword

nonn

Author

Sean A. Irvine, Oct 24 2023

Status

approved