OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = Sum_{d|n} phi(n/d) * tau(d^d).
If p is prime, a(p) = 2*p.
MATHEMATICA
Table[Sum[DivisorSigma[0, GCD[k, n]^(GCD[k, n])], {k, n}], {n, 100}] (* Giorgos Kalogeropoulos, May 13 2021 *)
PROG
(PARI) a(n) = sum(k=1, n, numdiv(gcd(k, n)^gcd(k, n)));
(PARI) a(n) = sumdiv(n, d, eulerphi(n/d)*numdiv(d^d));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 12 2021
STATUS
approved