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

A052666

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

Terms

    a(0) =1a(1) =1a(2) =8a(3) =42a(4) =456a(5) =4800a(6) =69840a(7) =1093680a(8) =20482560a(9) =420577920a(10) =9736070400a(11) =245887488000

External references