Floor(average of first n factorials).

Terms

a(0) =1a(1) =1a(2) =3a(3) =8a(4) =30a(5) =145a(6) =844a(7) =5779a(8) =45457a(9) =403791a(10) =3995883a(11) =43579692a(12) =519229008a(13) =6709162022a(14) =93440175754