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

Terms

a(0) =0a(1) =1a(2) =2a(3) =7a(4) =14a(5) =34a(6) =68a(7) =146a(8) =292a(9) =599a(10) =1198a(11) =2417a(12) =4834a(13) =9696a(14) =19392a(15) =38820a(16) =77640a(17) =155325a(18) =310650a(19) =621355a(20) =1242710a(21) =2485486a(22) =4970972a(23) =9942022a(24) =19884044a(25) =39768179a(26) =79536358a(27) =159072821a(28) =318145642a(29) =636291404