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A054934
Number of oriented graphs on n nodes up to reversing the arcs.
1
1, 2, 6, 30, 342, 11164, 1077370, 287640989, 207974848520, 408004023529326, 2187203136795598146, 32269918474347692838600, 1318898367787065334889143452, 150182948079490899321955309512894, 47886343174490577986560743878301096450, 42944209124580582731273744197913175367709988
OFFSET
1,2
LINKS
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
Sequence in context: A064847 A242996 A127815 * A001684 A076926 A092023
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