A054959 Number of labeled connected Eulerian digraphs with n nodes and an odd number of edges.

0, 0, 2, 56, 3488, 664688, 434127152, 1019647579136, 8819902136934912, 284798318582888580608, 34636901578294133260750592, 15970288165992077917878979939328, 28060652850285225214988677641875677184, 188680826646319054103468721801532834939660288

Offset: 1

Author

N. J. A. Sloane, May 24 2000

Keywords

• nonn
• easy

Links

• V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.

Crossrefs

Cf. A058338, A054955, A007080, A054956, A058337, A054958, A054957.

Programs

Mathematica

A054957 = Cases[Import["https://oeis.org/A054957/b054957.txt", "Table"], {, }][[All, 2]];
a[n_] := (A054957[[n]] - (n - 1)!)/2;
Array[a, 14] (* Jean-François Alcover, Sep 13 2019 *)

Formula

a(n) = (A054957(n) - (n-1)!)/2. - Andrew Howroyd, Sep 10 2018

Extensions

More terms from Vladeta Jovovic, Mar 06 2001

a(12)-a(14) from Andrew Howroyd, Sep 10 2018