A054934 Number of oriented graphs on n nodes up to reversing the arcs.

1, 2, 6, 30, 342, 11164, 1077370, 287640989, 207974848520, 408004023529326, 2187203136795598146, 32269918474347692838600, 1318898367787065334889143452, 150182948079490899321955309512894, 47886343174490577986560743878301096450, 42944209124580582731273744197913175367709988

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..50

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

Formula

Average of A001174 and A005639.

Mathematica

A001174 = Cases[Import["https://oeis.org/A001174/b001174.txt", "Table"], {_, _}][[All, 2]];
A005639 = Cases[Import["https://oeis.org/A005639/b005639.txt", "Table"], {_, _}][[All, 2]];
a[n_] := (A001174[[n]] + A005639[[n]])/2;
Array[a, 50] (* Jean-François Alcover, Sep 01 2019 *)

Crossrefs

Cf. A001174, A005639.

Sequence in context: A064847 A242996 A127815 * A001684 A076926 A092023

Adjacent sequences: A054931 A054932 A054933 * A054935 A054936 A054937

Keyword

nonn,easy

Author

N. J. A. Sloane, May 24 2000

Extensions

More terms from Philip Sung (phil(AT)main.nu), May 07 2001

Terms a(15) and beyond from Andrew Howroyd, Sep 16 2018

Status

approved