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 1-7 of 7 results.

A006823 Number of connected trivalent bipartite graphs with 2n nodes.

Original entry on oeis.org

1, 1, 2, 5, 13, 38, 149, 703, 4132, 29579, 245627, 2291589, 23466857, 259974248, 3087698618, 39075020582, 524492748500, 7439833931266, 111179110620163, 1745593888011626, 28726140345832290, 494406533261250407, 8881990236308687928, 166255686198172837111, 3237191621055524796848, 65467841616499410561220
Offset: 3

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Author

Keywords

References

  • CRC Handbook of Combinatorial Designs, 1996, p. 648.
  • I. A. Faradzev, Constructive enumeration of combinatorial objects, pp. 131-135 of Problèmes combinatoires et théorie des graphes (Orsay, 9-13 Juillet 1976). Colloq. Internat. du C.N.R.S., No. 260, Centre Nat. Recherche Scient., Paris, 1978.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column 3 of A008326.
Cf. A006824, A008325 (Euler transform).

Extensions

Terms a(17) and beyond from Andrew Howroyd, Apr 03 2020

A008327 Triangle read by rows: T(n,k) is the number of simple regular bipartite graphs with 2n nodes and degree k, (0 <= k <= n).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 4, 6, 4, 1, 1, 1, 1, 4, 14, 14, 4, 1, 1, 1, 1, 7, 41, 130, 41, 7, 1, 1, 1, 1, 8, 157, 1981, 1981, 157, 8, 1, 1, 1, 1, 12, 725, 62616, 304496, 62616, 725, 12, 1, 1, 1, 1, 14, 4196, 2806508, 78322916
Offset: 0

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Comments

This sequence can be derived from A008326 by Euler transform. - Andrew Howroyd, Apr 03 2020

Examples

			Triangle begins:
  1,
  1, 1,
  1, 1, 1,
  1, 1, 1,   1,
  1, 1, 2,   1,    1,
  1, 1, 2,   2,    1,    1,
  1, 1, 4,   6,    4,    1,   1;
  1, 1, 4,  14,   14,    4,   1, 1;
  1, 1, 7,  41,  130,   41,   7, 1, 1;
  1, 1, 8, 157, 1981, 1981, 157, 8, 1, 1;
  ...
		

Crossrefs

Column k=0..5 are A000012, A000012, A002865, A008325, A333730, A333731.
Row sums are A008324.

Formula

Column k is the Euler transform of column k of A008326. - Andrew Howroyd, Apr 03 2020

Extensions

More terms from Eric Rogoyski, May 15 1997
Name clarified by Andrew Howroyd, Sep 05 2018

A006824 Number of connected regular bipartite graphs of degree 4 with 2n nodes.

Original entry on oeis.org

1, 1, 4, 14, 129, 1980, 62611, 2806490, 158937213, 10773251972, 855658082615, 78558949838723, 8251166737356319, 982806379842257309, 131756174189661102281, 19748565896506014747623, 3289970433888731383271400, 605948436052375098046655323, 122796503871896458570959144266
Offset: 4

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Author

Keywords

References

  • CRC Handbook of Combinatorial Designs, 1996, p. 648.
  • I. A. Faradzev, Constructive enumeration of combinatorial objects, pp. 131-135 of Problèmes combinatoires et théorie des graphes (Orsay, 9-13 Juillet 1976). Colloq. Internat. du C.N.R.S., No. 260, Centre Nat. Recherche Scient., Paris, 1978.
  • H. Gropp, On tactical configurations, regular bipartite graphs and (v,k,even)-designs, Discr. Math., 155 (1996), 81-98.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column 4 of A008326.

Formula

Inverse Euler transform of A333730. - Andrew Howroyd, Apr 03 2020

Extensions

Terms a(12) and beyond from Andrew Howroyd, Apr 03 2020

A006825 Number of connected regular bipartite graphs of degree 5 with 2n nodes.

Original entry on oeis.org

1, 1, 4, 41, 1981, 304495, 78322915, 27033154060, 11934777413004, 6593485023087880, 4485517185017428244, 3707462300996566329965, 3680029088808677189795063, 4341813441626419937873317841, 6033239205199247162872884404386, 9792722283774374706204648839780148
Offset: 5

Views

Author

Keywords

References

  • CRC Handbook of Combinatorial Designs, 1996, p. 648.
  • I. A. Faradzev, Constructive enumeration of combinatorial objects, pp. 131-135 of Problèmes combinatoires et théorie des graphes (Orsay, 9-13 Juillet 1976). Colloq. Internat. du C.N.R.S., No. 260, Centre Nat. Recherche Scient., Paris, 1978.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column 5 of A008326.

Formula

Inverse Euler transform of A333731. - Andrew Howroyd, Apr 03 2020

Extensions

More terms from Eric Rogoyski, May 15 1997
Terms a(12) and beyond from Andrew Howroyd, Apr 03 2020

A008323 Number of simple connected regular bipartite graphs with 2n nodes.

Original entry on oeis.org

1, 1, 1, 2, 3, 5, 12, 34, 218, 4278, 431165, 162267174, 201636689352, 777816803938932, 9865957936943859185, 395886667549681686369527, 53716176608076643470380213991, 23524515269630339982914608683548933, 35682168849414944013547274439525153167248
Offset: 0

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Keywords

Crossrefs

For n > 1, these are the row sums of triangle A008326.

Extensions

a(10) corrected and a(11) added by Brendan McKay, Sep 06 2018
a(0)=1 prepended and terms a(12) and beyond from Andrew Howroyd, Apr 03 2020

A014385 Number of connected regular bipartite graphs of degree 6 with 2n nodes.

Original entry on oeis.org

1, 1, 7, 157, 62616, 78322916, 147252447227, 376962851057234, 1280344203366849969, 5666901233595672365908, 32193489258177947645878365, 231605871969834571512497704231, 2084558172807256752718977250960988
Offset: 6

Views

Author

Keywords

References

  • CRC Handbook of Combinatorial Designs, 1996, p. 648.
  • I. A. Faradzev, Constructive enumeration of combinatorial objects, pp. 131-135 of Problèmes combinatoires et théorie des graphes (Orsay, 9-13 Juillet 1976). Colloq. Internat. du C.N.R.S., No. 260, Centre Nat. Recherche Scient., Paris, 1978.

Crossrefs

Column k=6 of A008326.

Extensions

More terms from Eric Rogoyski, May 15 1997
a(12)-a(18) from Andrew Howroyd, Apr 04 2020

A014387 Number of connected regular bipartite graphs of degree 7 with 2n nodes.

Original entry on oeis.org

1, 1, 8, 725, 2806508, 27033154065, 376962851057235, 7292080848843162283, 192271946945501178473766, 6811960423672201527406129366, 320020341797819074616734725607588, 19688392653216509161510863093984500501
Offset: 7

Views

Author

Keywords

References

  • I. A. Faradzev, Constructive enumeration of combinatorial objects, pp. 131-135 of Problèmes combinatoires et théorie des graphes (Orsay, 9-13 Juillet 1976). Colloq. Internat. du C.N.R.S., No. 260, Centre Nat. Recherche Scient., Paris, 1978.
  • CRC Handbook of Combinatorial Designs, 1996, p. 648.

Crossrefs

Column k=7 of A008326.

Extensions

More terms from Eric Rogoyski, May 15 1997
a(12)-a(18) from Andrew Howroyd, Apr 04 2020
Showing 1-7 of 7 results.