a(n) is the smallest k >= 1 such that the expansion of the inverse of the k-th cyclotomic polynomial has n or -n as a coefficient, or -1 if no such k exists.

A131672

a(n) is the smallest k >= 1 such that the expansion of the inverse of the k-th cyclotomic polynomial has n or -n as a coefficient, or -1 if no such k exists.