A342396 a(n) = Sum_{k=1..n} k^(n/gcd(k,n) - 1).

1, 2, 6, 31, 355, 3150, 67172, 904085, 22998481, 427799450, 14914341926, 287337926355, 13421957361111, 339940911160914, 15434209582905140, 493467700905592777, 28101527071305611529, 836396358233559195382

Offset: 1

Author

Seiichi Manyama, Mar 10 2021

Keywords

• nonn
• easy

Crossrefs

Cf. A031971, A332621, A342394, A342395.

Programs

Mathematica

a[n_] := Sum[k^(n/GCD[k, n] - 1), {k, 1, n}]; Array[a, 18] (* Amiram Eldar, Mar 10 2021 *)

PARI

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

Formula

If p is prime, a(p) = A031971(p-1) + 1.