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

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

Offset: 4

Author

N. J. A. Sloane

Keywords

• nonn
• hard
• nice

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).

Links

• B. D. McKay and E. Rogoyski, Latin squares of order ten, Electron. J. Combinatorics, 2 (1995) #N3.
• M. Meringer, Tables of Regular Graphs

Crossrefs

Column 4 of A008326.

Cf. A006823, A006825, A333730.

Formula

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

Extensions

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