A054958 Number of labeled connected Eulerian digraphs with n nodes and an even number of edges.

1, 1, 4, 62, 3512, 664808, 434127872, 1019647584176, 8819902136975232, 284798318582888943488, 34636901578294133264379392, 15970288165992077917879019856128, 28060652850285225214988677642354678784, 188680826646319054103468721801532841166681088

Offset

1,3

Links

Table of n, a(n) for n=1..14.

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

Formula

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

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 *)

Crossrefs

Cf. A058338, A054955, A007080, A054959, A054956, A058337, A054957.

Sequence in context: A332694 A277392 A349068 * A191300 A087613 A350282

Adjacent sequences: A054955 A054956 A054957 * A054959 A054960 A054961

Keyword

nonn,easy

Author

N. J. A. Sloane, May 24 2000

Extensions

More terms from Vladeta Jovovic, Mar 06 2001

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

Status

approved