1181952200domain: NAppears in sequencesNumber of walks of length n on square lattice, starting at origin, staying in first quadrant.at n=17A005566Norm of coefficients in g.f. C(x) that satisfies: C(x) = 1 + x/C(I*x).at n=37A193384a(n) = binomial(2*n, n) * binomial(2*n - 1, n).at n=9A361877