A342394 a(n) = Sum_{k=1..n} k^(gcd(k,n) - 1).

1, 3, 11, 68, 629, 7793, 117655, 2097228, 43046772, 1000000649, 25937424611, 743008379146, 23298085122493, 793714773371841, 29192926025401528, 1152921504608945960, 48661191875666868497, 2185911559738739835591, 104127350297911241532859

Offset: 1

Author

Seiichi Manyama, Mar 10 2021

Keywords

• nonn
• easy

Crossrefs

Cf. A056665, A173235, A342389, A342396.

Programs

Mathematica

a[n_] := Sum[k^(GCD[k, n] - 1), {k, 1, n}]; Array[a, 19] (* Amiram Eldar, Mar 10 2021 *)

PARI

a(n) = sum(k=1, n, k^(gcd(k, n)-1));

Formula

If p is prime, a(p) = p-1 + p^(p-1) = A173235(p) = A056665(p).