OFFSET
1,2
COMMENTS
If p is prime, a(p) = Sum_{d|p} floor(p/d^2) = p + 0 = p.
If n = p^k where p is prime and k is a positive integer, then a(p^k) = Sum_{i=1..floor(k/2)+1} p^(k-2*i+2).
MATHEMATICA
Table[Sum[(1 - Ceiling[n/k] + Floor[n/k]) Floor[n/k^2], {k, n}], {n, 100}]
PROG
(PARI) a(n) = sumdiv(n, d, n\d^2); \\ Michel Marcus, May 17 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, May 16 2021
STATUS
approved