Partial sums of quadruple factorial numbers n!!!! (A007662).

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =11a(5) =16a(6) =28a(7) =49a(8) =81a(9) =126a(10) =246a(11) =477a(12) =861a(13) =1446a(14) =3126a(15) =6591a(16) =12735a(17) =22680a(18) =52920a(19) =118755a(20) =241635a(21) =450480a(22) =1115760a(23) =2629965a(24) =5579085a(25) =10800210a(26) =28097490a(27) =68981025a(28) =151556385a(29) =302969010