OFFSET
1,2
MATHEMATICA
a[n_] := Sum[k^(GCD[k, n] - 1), {k, 1, n}]; Array[a, 19] (* Amiram Eldar, Mar 10 2021 *)
PROG
(PARI) a(n) = sum(k=1, n, k^(gcd(k, n)-1));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Mar 10 2021
STATUS
approved