Expansion of Product_{k>=1} (1/(1 + 3*x^k))^k.

Terms

a(0) =1a(1) =-3a(2) =3a(3) =-18a(4) =69a(5) =-168a(6) =504a(7) =-1578a(8) =4800a(9) =-14310a(10) =42396a(11) =-128049a(12) =385839a(13) =-1154271a(14) =3458847a(15) =-10386477a(16) =31173873a(17) =-93490386a(18) =280426833a(19) =-841384614a(20) =2524300014a(21) =-7572585150a(22) =22717270491a(23) =-68152872885a(24) =204460229394a(25) =-613377236379