E.g.f. (1-sqrt(1-4*x-4*x^2))/ (2*(1+x)).

A052726

E.g.f. (1-sqrt(1-4*x-4*x^2))/ (2*(1+x)).

Terms

    a(0) =0a(1) =1a(2) =2a(3) =18a(4) =216a(5) =3720a(6) =81360a(7) =2172240a(8) =68423040a(9) =2484639360a(10) =102190636800

External references