OFFSET
1,2
COMMENTS
If p is prime, a(p) = p * Sum_{d|p} d^mu(p/d) = p * (1 + p^1) = p * (p + 1).
EXAMPLE
a(4) = 4 * Sum_{d|4} d^mu(4/d) = 4 * (1^0 + 2^(-1) + 4^1) = 22.
MATHEMATICA
Table[n*Sum[i^MoebiusMu[n/i] (1 - Ceiling[n/i] + Floor[n/i]), {i, n}], {n, 80}]
PROG
(PARI) a(n) = n*sumdiv(n, d, d^moebius(n/d)); \\ Michel Marcus, May 25 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, May 24 2021
STATUS
approved