18985057351domain: NAppears in sequencesRiordan numbers: a(n) = (n-1)*(2*a(n-1) + 3*a(n-2))/(n+1).at n=27A005043Bisection of A005043.at n=13A099252First column of A174295.at n=29A174297a(n) = [x^n] (1 - 2*x - sqrt((1 - 3*x)/(1 + x)))/(2*x^3).at n=25A342912