G.f. satisfies: A(x) = x + A( A(x)^2 - A(x)^6 ).

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =20a(5) =71a(6) =264a(7) =1018a(8) =4032a(9) =16305a(10) =67042a(11) =279444a(12) =1178088a(13) =5014596a(14) =21521488a(15) =93027025a(16) =404630318a(17) =1769704106a(18) =7778030834a(19) =34335337802a(20) =152168657438a(21) =676796514510