a(0) = 0, a(1) = 1 and a(n) = 2*a(n-1)/(n-1) + 16*a(n-2) for n > 1.

Terms

a(0) =0a(1) =1a(2) =2a(3) =18a(4) =44a(5) =310a(6) =828a(7) =5236a(8) =14744a(9) =87462a(10) =255340a(11) =1450460a(12) =4349160a(13) =23932220a(14) =73268440a(15) =393382440a(16) =1224746032a(17) =6447212294a(18) =20354432076a(19) =105417000268a(20) =336767439560