Expansion of o.g.f. x^4/((1-2*x)^3*(1-3*x)^3).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =15a(6) =132a(7) =890a(8) =5091a(9) =26025a(10) =122590a(11) =542700a(12) =2288565a(13) =9282275a(14) =36469704a(15) =139556910a(16) =522324343a(17) =1918424685a(18) =6933067554a(19) =24707355200a(20) =86980866345a(21) =302944443975