E.g.f.: (1-x)/(1-3*x+x^2).

A052568

E.g.f.: (1-x)/(1-3*x+x^2).

Terms

    a(0) =1a(1) =2a(2) =10a(3) =78a(4) =816a(5) =10680a(6) =167760a(7) =3074400a(8) =64391040a(9) =1517201280a(10) =39720844800

External references