OFFSET
1,2
MATHEMATICA
a[n_] := Sum[GCD[k, n]^(k - 2), {k, 1, n}]; Array[a, 20] (* Amiram Eldar, Mar 13 2021 *)
PROG
(PARI) a(n) = sum(k=1, n, gcd(k, n)^(k-2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 13 2021
STATUS
approved