A binomial transform of factorial numbers.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =21a(6) =52a(7) =134a(8) =361a(9) =1009a(10) =2926a(11) =8768a(12) =27121a(13) =86373a(14) =282864a(15) =950866a(16) =3277169a(17) =11564353a(18) =41739130a(19) =153919324a(20) =579411641a(21) =2224535125a(22) =8703993420a(23) =34681783422a(24) =140637608089a(25) =580019801201