a(n) = n*(a(n-1)+3), a(0)=1.

Terms

a(0) =1a(1) =4a(2) =14a(3) =51a(4) =216a(5) =1095a(6) =6588a(7) =46137a(8) =369120a(9) =3322107a(10) =33221100a(11) =365432133a(12) =4385185632a(13) =57007413255a(14) =798103785612