Expansion of x^4/[(1+x)*Product_{k=1..3} (1-k*x)].

Terms

a(0) =1a(1) =5a(2) =20a(3) =70a(4) =231a(5) =735a(6) =2290a(7) =7040a(8) =21461a(9) =65065a(10) =196560a(11) =592410a(12) =1782691a(13) =5358995a(14) =16098830a(15) =48340180a(16) =145107921a(17) =435498525a(18) =1306845100a(19) =3921234350a(20) =11765101151a(21) =35298099655a(22) =105899891370a(23) =317710858920a(24) =953154946381