G.f. A(x) satisfies: A(x) = (1 - x^2*A(x)^2)/(1 - x^2*A(x)^2 - x^3*A(x)^3).

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =0a(5) =1a(6) =4a(7) =1a(8) =10a(9) =23a(10) =18a(11) =92a(12) =168a(13) =241a(14) =856a(15) =1480a(16) =2904a(17) =8266a(18) =14854a(19) =33496a(20) =83578a(21) =161047a(22) =380488a(23) =884326a(24) =1819714a(25) =4321045a(26) =9730466a(27) =21019404a(28) =49456092a(29) =110408981