Bisection of A000081 (odd part).

Terms

a(0) =1a(1) =2a(2) =9a(3) =48a(4) =286a(5) =1842a(6) =12486a(7) =87811a(8) =634847a(9) =4688676a(10) =35221832a(11) =268282855a(12) =2067174645a(13) =16083734329a(14) =126186554308a(15) =997171512998