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A363650
Expansion of Sum_{k>0} x^k/(1 - (k*x)^k)^3.
5
1, 4, 7, 23, 16, 199, 29, 1445, 4420, 13271, 67, 751597, 92, 2585423, 66565486, 218693769, 154, 14527231822, 191, 399614708821, 4080186211018, 856004218103, 277, 2754664372347481, 1430511474609701, 908626846503767, 900580521111136750, 5626675967703843613, 436
OFFSET
1,2
FORMULA
a(n) = Sum_{d|n} (n/d)^(n-n/d) * binomial(d+1,2).
MATHEMATICA
a[n_] := DivisorSum[n, (n/#)^(n-n/#) * Binomial[# + 1, 2] &]; Array[a, 30] (* Amiram Eldar, Jul 18 2023 *)
PROG
(PARI) a(n) = sumdiv(n, d, (n/d)^(n-n/d)*binomial(d+1, 2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 13 2023
STATUS
approved