132448domain: NAppears in sequencesNumber of n-fold branched coverings of the projective plane with r cyclic branch points (n,r>=1); array read by downward antidiagonals.at n=40A113949G.f. A(x) satisfies: A(x) = x + 2*A(x^2) + 4*A(x^3) + 8*A(x^4) + ... + 2^(k-1)*A(x^k) + ...at n=17A308076