A054953 Number of unlabeled semi-strong digraphs on n nodes with an odd number of pairwise different components.

1, 1, 5, 83, 5048, 1047013, 705422455, 1580348377261, 12139024826336632, 328160951350054991463, 31831080872414173375174213, 11234274997368911879051177335450, 14576252633139821208116086572516525403, 70075713785837731364265242597960381223077163

Offset

1,3

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

a(n) = (A054952(n) + A054951(n))/2. - Andrew Howroyd, Sep 10 2018

Mathematica

m = 15;
A035512 = Cases[Import["https://oeis.org/A035512/b035512.txt", "Table"], {_, _}][[All, 2]];
gf = -Product[(1 - x^n)^A035512[[n + 1]], {n, 1, m}] + Product[(1 + x^n)^A035512[[n + 1]], {n, 1, m}];
CoefficientList[gf + O[x]^m , x]/2 // Rest (* Jean-François Alcover, Aug 26 2019, after Andrew Howroyd *)

Crossrefs

Cf. A054951, A054952, A054954.

Sequence in context: A348791 A250549 A035512 * A215172 A301811 A216146

Adjacent sequences: A054950 A054951 A054952 * A054954 A054955 A054956

Keyword

nonn,easy

Author

N. J. A. Sloane, May 24 2000

Extensions

More terms from Vladeta Jovovic, Mar 11 2003

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

Status

approved