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A363646
Expansion of Sum_{k>0} (1/(1 - (k*x)^k)^2 - 1).
6
2, 11, 58, 565, 6256, 95762, 1647094, 33752329, 774919720, 20029303030, 570623341234, 17838801038274, 605750213184520, 22226048320465666, 875787902918124708, 36894332593824661521, 1654480523772673528372, 78693266840741507386757
OFFSET
1,1
FORMULA
a(n) = Sum_{d|n} (n/d)^n * (d+1).
MATHEMATICA
a[n_] := DivisorSum[n, (n/#)^n * (# + 1) &]; Array[a, 20] (* Amiram Eldar, Jul 17 2023 *)
PROG
(PARI) a(n) = sumdiv(n, d, (n/d)^n*(d+1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 13 2023
STATUS
approved