Number of functional patterns on n elements; or digraphs with maximum outdegree 1, n arrows and every point connected to an arrow.

A116950

Number of functional patterns on n elements; or digraphs with maximum outdegree 1, n arrows and every point connected to an arrow.

Terms

    a(0) =1a(1) =2a(2) =7a(3) =20a(4) =61a(5) =174a(6) =514a(7) =1478a(8) =4303a(9) =12437a(10) =36084a(11) =104494a(12) =303167a(13) =879283a(14) =2552803a(15) =7413583a(16) =21544347a(17) =62635823a(18) =182199853a(19) =530228946a(20) =1543761513a(21) =4496523995a(22) =13102414665a(23) =38193626823a(24) =111375529695a(25) =324891970936a(26) =948051861938

External references