Number of unlabeled semitransitive orders on n elements: (1+3)-free posets.

A079146

Number of unlabeled semitransitive orders on n elements: (1+3)-free posets.

Terms

    a(0) =1a(1) =2a(2) =5a(3) =15a(4) =49a(5) =173a(6) =639a(7) =2469a(8) =9997a(9) =43109a(10) =205092a(11) =1153646a(12) =8523086a(13) =91156133a(14) =1446766659a(15) =32998508358

External references