Total preorders.

Terms

a(0) =1a(1) =5a(2) =24a(3) =122a(4) =680a(5) =4155a(6) =27776a(7) =202084a(8) =1592064a(9) =13513825a(10) =123025408a(11) =1196165886a(12) =12374422528a(13) =135740585015