login
This site is supported by donations to The OEIS Foundation.

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A014377 Number of connected regular graphs of degree 7 with 2n nodes. 20
1, 0, 0, 0, 1, 5, 1547, 21609301, 733351105934 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

REFERENCES

CRC Handbook of Combinatorial Designs, 1996, p. 648.

I. A. Faradzev, Constructive enumeration of combinatorial objects, pp. 131-135 of Probl\`{e}mes combinatoires et th\'{e}orie des graphes (Orsay, 9-13 Juillet 1976). Colloq. Internat. du C.N.R.S., No. 260, Centre Nat. Recherche Scient., Paris, 1978.

LINKS

Table of n, a(n) for n=0..8.

Jason Kimberley, Index of sequences counting connected k-regular simple graphs with girth at least g

M. Meringer, Tables of Regular Graphs

Eric Weisstein's World of Mathematics, Regular Graph

FORMULA

a(n) = A184973(n) + A181153(n).

a(n) = A165628(n) - A165877(n).

This sequence is the inverse Euler transformation of A165628.

EXAMPLE

a(0)=1 because the null graph (with no vertices) is vacuously 7-regular and connected.

CROSSREFS

Contribution (almost all) from Jason Kimberley, Feb 10 2011: (Start)

7-regular simple graphs: this sequence (connected), A165877 (disconnected), A165628 (not necessarily connected).

Connected regular simple graphs A005177 (any degree), A068934 (triangular array), specified degree k: A002851 (k=3), A006820 (k=4), A006821 (k=5), A006822 (k=6), this sequence (k=7), A014378 (k=8), A014381 (k=9), A014382 (k=10), A014384 (k=11).

Connected 7-regular simple graphs with girth at least g: this sequence (g=3), A181153 (g=4).

Connected 7-regular simple graphs with girth exactly g: A184963 (g=3), A184964 (g=4), A184965 (g=5). (End)

Sequence in context: A184970 A184973 A184971 * A165628 A119747 A177906

Adjacent sequences:  A014374 A014375 A014376 * A014378 A014379 A014380

KEYWORD

nonn,nice,hard,more

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Added another term from Meringer's page. Dmitry Kamenetsky, Jul 28 2009

Term a(8) (on Meringer's page) was found from running Meringer's GENREG for 325 processor days at U. Newcastle by Jason Kimberley, Oct 02 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified September 1 03:55 EDT 2014. Contains 246282 sequences.