a(0)=0; for n>0, a(n) = (n+2)*a(n-1) + 1.

Terms

a(0) =0a(1) =1a(2) =5a(3) =26a(4) =157a(5) =1100a(6) =8801a(7) =79210a(8) =792101a(9) =8713112a(10) =104557345a(11) =1359245486a(12) =19029436805a(13) =285441552076