3264864domain: NAppears in sequencesE.g.f.: S(x,q) = Integral C(x,q) * C(q*x,q) dx, such that C(x,q)^2 - S(x,q)^2 = 1, where S(x,q) = Sum_{n>=0} sum_{k=0..n*(n+1)/2} T(n,k)*x^n*y^k/n!, as an irregular triangle of coefficients T(n,k) read by rows.at n=50A322219Expansion of sqrt(1 - 4*x*sqrt(1 - 4*x)).at n=15A377243