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

Terms

a(0) =1a(1) =2a(2) =4a(3) =12a(4) =40a(5) =128a(6) =416a(7) =1344a(8) =4224a(9) =12928a(10) =38016a(11) =104832a(12) =260096a(13) =512256a(14) =329728a(15) =-4140032a(16) =-33444864a(17) =-184423424a(18) =-883798016a(19) =-3935711232a(20) =-16759001088a(21) =-69266997248a(22) =-280327684096