G.f.: (2*x^2+4*x+3)/((2*x+2)*sqrt(-4*x^3-4*x^2+1))-1/(2*x+2).

Terms

a(0) =1a(1) =1a(2) =3a(3) =4a(4) =11a(5) =21a(6) =48a(7) =106a(8) =235a(9) =535a(10) =1203a(11) =2751a(12) =6272a(13) =14392a(14) =33078a(15) =76224a(16) =176043a(17) =407253a(18) =943833a(19) =2190397a(20) =5090371a(21) =11843689a(22) =27586793a(23) =64320191a(24) =150102784a(25) =350586496a(26) =819477792a(27) =1916861350a(28) =4486760870a(29) =10508582130