Expansion of 1/(1-4*x)^(21/2).

Terms

a(0) =1a(1) =42a(2) =966a(3) =16100a(4) =217350a(5) =2521260a(6) =26053020a(7) =245642760a(8) =2149374150a(9) =17672631900a(10) =137846528820