OFFSET
1,2
FORMULA
a(n) = Sum_{k=1..n} (lcm(n, k)/n)^n.
a(n) = Sum_{d|n} Sum_{k=1..d, gcd(k, d) = 1} k^n.
MATHEMATICA
Table[Sum[(k/GCD[n, k])^n, {k, 1, n}], {n, 1, 20}]
Table[Sum[Sum[If[GCD[k, d] == 1, k^n, 0], {k, 1, d}], {d, Divisors[n]}], {n, 1, 20}]
PROG
(Magma) [&+[(k div Gcd(n, k))^n:k in [1..n]]:n in [1..20]]; // Marius A. Burtea, Feb 18 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 18 2020
STATUS
approved