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A372701
a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} mu(i*j*k), where mu is the Moebius function A008683.
0
1, -2, 1, 1, 4, 1, -2, -2, -2, -5, -8, -8, -17, -2, 7, 7, 16, 16, 19, 19, 58, 79, 112, 112, 112, 151, 151, 151, 202, 115, 124, 124, 181, 238, 235, 235, 304, 355, 334, 334, 445, 232, 289, 289, 289, 358, 439, 439, 439, 439, 436, 436, 535, 535, 538, 538, 523, 508, 685, 685, 862, 913, 913, 913, 820, 421
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