OFFSET
1,2
MATHEMATICA
Table[Sum[MoebiusMu[i*j*k], {i, 1, n}, {j, 1, n}, {k, 1, n}], {n, 1, 80}] (* Vaclav Kotesovec, Jun 01 2024 *)
PROG
(PARI) a(n) = sum(i=1, n, sum(j=1, n, sum(k=1, n, moebius(i*j*k))));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, May 10 2024
STATUS
approved