Number of tree interval posets of permutations of size n, considered up to isomorphism.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =6a(5) =14a(6) =32a(7) =79a(8) =192a(9) =488a(10) =1244a(11) =3240a(12) =8497a(13) =22561a(14) =60309a(15) =162541a(16) =440598a(17) =1201377a(18) =3291426a(19) =9058464a(20) =25027797a(21) =69401101a(22) =193071153a(23) =538724060a(24) =1507288378a(25) =4227824974a(26) =11886150870a(27) =33488522111a(28) =94539554742a(29) =267383598840