Number of power series 1 + c_1*x^1 + c_2*x^2 + ... + c_{n-1}*x^{n-1} + O(x^n) with c_k in {-1, 0, 1} whose reciprocal has the same property.

A244629

Number of power series 1 + c_1*x^1 + c_2*x^2 + ... + c_{n-1}*x^{n-1} + O(x^n) with c_k in {-1, 0, 1} whose reciprocal has the same property.