A166387 a(n) = sum (floor (j^2/n), 1 <= j <= n-1) - floor ((n-1)(n-2)/3), n >= 2.

0, 1, 1, 0, 1, 1, 2, 2, 0, 1, 3, 0, 1, 3, 4, 0, 2, 1, 3, 2, 1, 3, 6, 2, 0, 3, 3, 0, 3, 3, 6, 2, 0, 3, 7, 0, 1, 5, 6, 0, 2, 1, 5, 4, 3, 5, 10, 4, 2, 3, 3, 0, 3, 5, 8, 2, 0, 3, 9, 0, 3, 7, 10, 0, 2, 1, 5, 4, 3, 7, 12, 0, 0, 7, 5, 2, 5, 5, 12, 6, 0, 3, 9, 0, 1, 7, 8, 0, 4, 3, 7, 4, 5, 9, 16, 0, 4