Species of ordered Latin bi-trades of size n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =0a(5) =1a(6) =1a(7) =5a(8) =4a(9) =19a(10) =26a(11) =163a(12) =445a(13) =2302a(14) =10798a(15) =63690a(16) =381883a(17) =2550827a(18) =17945643