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A332652

a(n) = Sum_{k=1..n} n^(k/gcd(n, k)).

1, 4, 15, 76, 785, 7836, 137263, 2130976, 47895489, 1010012140, 28531167071, 743044702104, 25239592216033, 797785008119932, 31147773583464735, 1157442765678719056, 51702516367896047777, 2185932446984222457444, 109912203092239643840239, 5255987282125826560192520

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..20.

FORMULA

a(n) = Sum_{k=1..n} n^(lcm(n, k)/n).

a(n) = Sum_{d|n} Sum_{k=1..d, gcd(k, d) = 1} n^k.

a(n) = n * A332653(n).

MATHEMATICA

Table[Sum[n^(k/GCD[n, k]), {k, 1, n}], {n, 1, 20}]

Table[Sum[Sum[If[GCD[k, d] == 1, n^k, 0], {k, 1, d}], {d, Divisors[n]}], {n, 1, 20}]