OFFSET
1,2
FORMULA
If p is prime, a(p) = Sum_{d^2|p} p^abs(mu(p-d)) = p^abs(mu(p-1)).
EXAMPLE
a(8) = Sum_{d^2|8} 8^abs(mu(8-d)) = 8^abs(mu(7)) + 8^abs(mu(6)) = 8^1 + 8^1 = 16.
MATHEMATICA
Table[Sum[n^(MoebiusMu[n - k]^2) (1 - Ceiling[n/k^2] + Floor[n/k^2]), {k, n}], {n, 100}]
PROG
(PARI) a(n) = if (n==1, 1, sumdiv(n, d, if (issquare(d), n^abs(moebius(n-sqrtint(d)))))); \\ Michel Marcus, Jun 08 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jun 07 2021
STATUS
approved