Expansion of B(x)/sqrt(1 + 2*(B(x)-1)), where B(x) is the g.f. of A000984.

Terms

a(0) =1a(1) =0a(2) =2a(3) =4a(4) =16a(5) =52a(6) =188a(7) =672a(8) =2458a(9) =9052a(10) =33648a(11) =125864a(12) =473500a(13) =1789632a(14) =6791528a(15) =25863568a(16) =98796096a(17) =378411332a(18) =1452886052a(19) =5590262688a(20) =21551271916a(21) =83228809640a(22) =321933018272