G.f. satisfies: A(x) = 1 + x^2 + x*A(x)^2.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =20a(5) =63a(6) =208a(7) =711a(8) =2496a(9) =8944a(10) =32578a(11) =120263a(12) =448938a(13) =1691776a(14) =6427130a(15) =24589043a(16) =94653498a(17) =366344216a(18) =1424750506a(19) =5565002716a(20) =21821377624a(21) =85867522754a(22) =338974659036