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

A052662

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

Terms

    a(0) =1a(1) =2a(2) =8a(3) =54a(4) =480a(5) =5400a(6) =72720a(7) =1144080a(8) =20563200a(9) =415860480a(10) =9344160000a(11) =230958604800

External references