Number of digraphs on n unlabeled nodes with a sink (or, with a source).

A051421

Number of digraphs on n unlabeled nodes with a sink (or, with a source).

Terms

    a(0) =1a(1) =2a(2) =12a(3) =185a(4) =8990a(5) =1505939a(6) =875542491

External references