Expansion of 1 + 2x/(1 + sqrt(1 - 4x^2)).

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =0a(5) =2a(6) =0a(7) =5a(8) =0a(9) =14a(10) =0a(11) =42a(12) =0a(13) =132a(14) =0a(15) =429a(16) =0a(17) =1430a(18) =0a(19) =4862a(20) =0a(21) =16796a(22) =0a(23) =58786a(24) =0a(25) =208012a(26) =0a(27) =742900a(28) =0a(29) =2674440