E.g.f. (1-x^2)/(1-2x-x^2).

A052622

E.g.f. (1-x^2)/(1-2x-x^2).

Terms

    a(0) =1a(1) =2a(2) =8a(3) =60a(4) =576a(5) =6960a(6) =100800a(7) =1703520a(8) =32901120a(9) =714873600a(10) =17258572800a(11) =458324697600

External references