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

Terms

a(0) =1a(1) =1a(2) =2a(3) =7a(4) =22a(5) =73a(6) =256a(7) =924a(8) =3414a(9) =12858a(10) =49174a(11) =190456a(12) =745552a(13) =2945084a(14) =11724892a(15) =46997221a(16) =189508278a(17) =768208478a(18) =3128783688a(19) =12796954158a(20) =52540280074a(21) =216460224040a(22) =894601743188