A variant of A000179 and A102761.

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =2a(5) =13a(6) =80a(7) =579a(8) =4738a(9) =43387a(10) =439792a(11) =4890741a(12) =59216642a(13) =775596313a(14) =10927434464a(15) =164806435783