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%I #7 Apr 17 2021 18:11:16
%S 1,2,18,84,355,645,2276,3192,7413,9400,25334,18395,60711,52747,88760,
%T 106688,243849,137790,432346,275570,499867,522513,1151404,561415,
%U 1542125,1214436,1907502,1569673,3756719,1344999,5274000,3451216,4970577,4690778,7499154,4217504,12948595,8207261,11565572
%N a(n) = Sum_{k=1..n} (k/gcd(n, k))^4.
%F a(n) = Sum_{d|n} A053820(d).
%t Table[Sum[(k/GCD[n, k])^4, {k, 1, n}], {n, 1, 39}]
%o (PARI) a(n) = sum(k=1, n, (k/gcd(n, k))^4); \\ _Michel Marcus_, Apr 17 2021
%Y Cf. A053820, A057661, A332654, A343498, A343513.
%K nonn
%O 1,2
%A _Ilya Gutkovskiy_, Apr 17 2021
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