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

A052608

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

Terms

    a(0) =1a(1) =1a(2) =6a(3) =42a(4) =408a(5) =4920a(6) =71280a(7) =1204560a(8) =23264640a(9) =505491840a(10) =12203654400a(11) =324084499200

External references