509136domain: NAppears in sequencesExpansion of series_reversion( x/(1+x^4*sum(k>=0, x^k)) ) / x.at n=25A215341G.f.: Sum_{n>=0} x^n / (1-3*x)^(2*n+1) * [Sum_{k=0..n} C(n,k)^2 * x^k] * [Sum_{k=0..n} C(n,k)^2 * 3^k * x^k].at n=7A246813