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A300548
a(n) = [x^n] Product_{d|n} 1/(1 + x^d).
2
1, -1, 0, -2, 0, -2, 0, -2, 0, -5, 1, -2, 1, -2, 0, -14, 0, -2, 1, -2, 0, -18, 0, -2, 0, -7, 1, -23, 0, -2, 6, -2, 0, -26, 1, -26, 4, -2, 0, -30, 0, -2, 6, -2, 1, -286, 0, -2, 0, -9, 7, -38, 0, -2, 8, -38, 1, -42, 1, -2, 7, -2, 0, -493, 0, -44, 9, -2, 0, -50, 10, -2, 0, -2, 1, -698, 1, -50, 12, -2, 0, -239, 1, -2, 10, -56
OFFSET
0,4
FORMULA
a(n) = -2 if n is an odd prime (A065091).
MATHEMATICA
Table[SeriesCoefficient[Product[1/(1 + Boole[Mod[n, k] == 0] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 85}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Mar 08 2018
STATUS
approved