cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-5 of 5 results.

A039750 Erroneous version of A058337.

Original entry on oeis.org

1, 1, 1, 3, 12, 68
Offset: 0

Views

Author

Keywords

References

  • F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 219.

A058338 Number of digraphs with indegree = outdegree at each vertex, or Eulerian digraphs (including disconnected graphs) with n nodes.

Original entry on oeis.org

1, 1, 2, 5, 18, 111, 2292, 181519, 51294836, 48814342597, 157166848652408, 1736132851915020181, 66689407510956897981608, 9012860249531358132125181323, 4328664025050045497712238253179872, 7451990930474005836163802713084971814275, 46329549163592383403451764167315165130121820112
Offset: 0

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Author

Keywords

Comments

Every regular tournament (A096368) is a Eulerian digraph. Similar methods may be used to compute terms of this sequence. - Andrew Howroyd, Apr 12 2020

References

  • F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 219 (but there is an error).
  • Ronald C. Read, email to N. J. A. Sloane, 28 August, 2000.

Crossrefs

Cf. A007080 (labeled), A058337 (connected), A096368, A308161, A308111.

Programs

Formula

Euler transform of A058337.

Extensions

a(7) added using A058337 by Falk Hüffner, Dec 03 2015
a(8) and a(9) added using A058337 by Brendan McKay, May 05 2019
Terms a(10) and beyond from Andrew Howroyd, Apr 12 2020

A054957 Number of labeled connected Eulerian digraphs with n nodes.

Original entry on oeis.org

1, 1, 6, 118, 7000, 1329496, 868255024, 2039295163312, 17639804273910144, 569596637165777524096, 69273803156588266525129984, 31940576331984155835757999795456, 56121305700570450429977355284230355968, 377361653292638108206937443603065676106341376
Offset: 1

Views

Author

N. J. A. Sloane, May 24 2000

Keywords

Crossrefs

Cf. A058338, A054955, A007080 (EXP-transform), A054959, A054956, A058337, A054958.

Formula

a(n) = A054958(n) + A054959(n). - R. J. Mathar, Apr 13 2017

Extensions

More terms from Vladeta Jovovic, Mar 06 2001
More terms from Alois P. Heinz, Apr 14 2017

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

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, May 24 2000

Keywords

Crossrefs

Programs

Formula

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

Extensions

More terms from Vladeta Jovovic, Mar 06 2001
a(12)-a(14) from Andrew Howroyd, Sep 10 2018

A054959 Number of labeled connected Eulerian digraphs with n nodes and an odd number of edges.

Original entry on oeis.org

0, 0, 2, 56, 3488, 664688, 434127152, 1019647579136, 8819902136934912, 284798318582888580608, 34636901578294133260750592, 15970288165992077917878979939328, 28060652850285225214988677641875677184, 188680826646319054103468721801532834939660288
Offset: 1

Views

Author

N. J. A. Sloane, May 24 2000

Keywords

Crossrefs

Programs

Formula

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

Extensions

More terms from Vladeta Jovovic, Mar 06 2001
a(12)-a(14) from Andrew Howroyd, Sep 10 2018
Showing 1-5 of 5 results.