Bisection of A014137.

Terms

a(0) =2a(1) =9a(2) =65a(3) =626a(4) =6918a(5) =82500a(6) =1033412a(7) =13402697a(8) =178405157a(9) =2423307047a(10) =33453694487a(11) =467995871777