A366820 - OEIS

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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

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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);