Coefficients of the solution to a functional equation.

Terms

a(0) =1a(1) =2a(2) =6a(3) =16a(4) =62a(5) =192a(6) =652a(7) =2048a(8) =9270a(9) =31744a(10) =116948a(11) =393216a(12) =1533868a(13) =5341184a(14) =19445016a(15) =67108864a(16) =332958758a(17) =1215037440a(18) =4711687300a(19) =16642998272a(20) =67697833092a(21) =245257732096a(22) =923984441000