Expansion of (1/x) * Series_Reversion( x * (1-x) / (1+x^2)^2 ).

Terms

a(0) =1a(1) =1a(2) =4a(3) =13a(4) =53a(5) =220a(6) =968a(7) =4373a(8) =20271a(9) =95705a(10) =458904a(11) =2228220a(12) =10934524a(13) =54143848a(14) =270189008a(15) =1357428997a(16) =6860264323a(17) =34853234867a(18) =177900211204a(19) =911867479717