OFFSET
1,2
MATHEMATICA
a[n_] := Sum[(-1)^(k + 1)*Floor[(n/k)^n], {k, 1, n}]; Array[a, 18] (* Amiram Eldar, Dec 20 2021 *)
PROG
(PARI) a(n) = sum(k=1, n, (-1)^(k+1)*(n^n\k^n));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 20 2021
STATUS
approved