Number of partially ordered sets ("posets") with n unlabeled elements.

A000112

Number of partially ordered sets ("posets") with n unlabeled elements.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =16a(5) =63a(6) =318a(7) =2045a(8) =16999a(9) =183231a(10) =2567284a(11) =46749427a(12) =1104891746a(13) =33823827452

External references