OFFSET
0,8
FORMULA
a(n) = Sum_{k=1..floor(n/4)} Sum_{j=k..floor((n-k)/3)} Sum_{i=j..floor((n-j-k)/3)} mu(k+j)^2 * mu(n-j-k)^2, where mu is the Möbius function (A008683).
MATHEMATICA
Table[Sum[Sum[Sum[MoebiusMu[k + j]^2*MoebiusMu[n - j - k]^2, {i, j, Floor[(n - j - k)/2]}], {j, k, Floor[(n - k)/3]}], {k, Floor[n/4]}], {n, 0, 80}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jan 19 2021
STATUS
approved