Series reversion of (sqrt(1+4*x) - 1)/2 - x^3.

Terms

a(0) =1a(1) =1a(2) =1a(3) =5a(4) =12a(5) =35a(6) =122a(7) =390a(8) =1320a(9) =4631a(10) =16185a(11) =57707a(12) =208348a(13) =756840a(14) =2775012a(15) =10246206a(16) =38043339a(17) =142045387a(18) =532888840a(19) =2007554241a(20) =7592537590a(21) =28814794105a(22) =109702322730a(23) =418868083725