a(n) = n! * Sum_{k=0..n} binomial(k+4,5) / k!.

Terms

a(0) =0a(1) =1a(2) =8a(3) =45a(4) =236a(5) =1306a(6) =8088a(7) =57078a(8) =457416a(9) =4118031a(10) =41182312a(11) =453008435a(12) =5436105588a(13) =70669378832a(14) =989371312216