Floor(compositorial(n) / n!), that is, floor(A036691(n) / A000142(n)).

Terms

a(0) =4a(1) =12a(2) =32a(3) =72a(4) =144a(5) =288a(6) =576a(7) =1080a(8) =1920a(9) =3456a(10) =6283a(11) =10996a(12) =18609a(13) =31901a(14) =53169a(15) =86400a(16) =137223a(17) =213458a(18) =337040a(19) =539264a(20) =847415a(21) =1309642a(22) =1992933a(23) =2989400a(24) =4543888a(25) =6815833a(26) =10097530a(27) =15146295a(28) =22980586a(29) =34470879