A343514 - OEIS

A343514

a(n) = Sum_{k=1..n} (k/gcd(n, k))^4.

1, 2, 18, 84, 355, 645, 2276, 3192, 7413, 9400, 25334, 18395, 60711, 52747, 88760, 106688, 243849, 137790, 432346, 275570, 499867, 522513, 1151404, 561415, 1542125, 1214436, 1907502, 1569673, 3756719, 1344999, 5274000, 3451216, 4970577, 4690778, 7499154, 4217504, 12948595, 8207261, 11565572

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..39.

FORMULA

a(n) = Sum_{d|n} A053820(d).

MATHEMATICA

Table[Sum[(k/GCD[n, k])^4, {k, 1, n}], {n, 1, 39}]

PROG

(PARI) a(n) = sum(k=1, n, (k/gcd(n, k))^4); \\ Michel Marcus, Apr 17 2021

CROSSREFS