OFFSET
1,3
COMMENTS
If p is prime, a(p) = Sum_{d|p} (p-d)^abs(mu(p/d)) = (p-1)^1 = p-1.
EXAMPLE
a(12) = Sum_{d|12} (12-d)^abs(mu(12/d)) = 11^0 + 10^1 + 9^0 + 8^1 + 6^1 + 0^1 = 26.
MATHEMATICA
Table[Sum[(n - k)^Abs[MoebiusMu[n/k]] (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jun 12 2021
STATUS
approved