OFFSET
1,3
COMMENTS
a(p) = p-1 for primes p.
MATHEMATICA
Table[Sum[(i!) (n - i) (1 - Ceiling[n/i] + Floor[n/i]), {i, n}], {n, 50}]
PROG
(PARI) a(n) = sumdiv(n, d, (n-d) * d!); \\ Michel Marcus, Oct 03 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Oct 02 2021
STATUS
approved