Number of functional digraphs (digraphs of functions on n nodes where every node has outdegree 1 and loops of length 1 are forbidden).

A001373

Number of functional digraphs (digraphs of functions on n nodes where every node has outdegree 1 and loops of length 1 are forbidden).

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =6a(5) =13a(6) =40a(7) =100a(8) =291a(9) =797a(10) =2273a(11) =6389a(12) =18264a(13) =51916a(14) =148666a(15) =425529a(16) =1221900a(17) =3511507a(18) =10111043a(19) =29142941a(20) =84112009a(21) =243000149a(22) =702758065a(23) =2034150215a(24) =5892907566a(25) =17084615940a(26) =49567063847a(27) =143902155133a(28) =418032946298

External references