A054934 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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;