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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A033483 Number of disconnected 4-valent (or quartic) graphs with n nodes. 18
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 3, 8, 25, 88, 378, 2026, 13351, 104595, 930586, 9124662, 96699987, 1095469608, 13175272208, 167460699184, 2241578965849 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,13

COMMENTS

Despite A006820(n) being currently unknown for n > 21, we can calculate this sequence A033483(n) up to n = 26, because the smallest 4-regular graph is K_5. - Jason Kimberley, Sep 27 2009

REFERENCES

R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.

LINKS

Table of n, a(n) for n=0..26.

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

N. J. A. Sloane, Transforms

Eric Weisstein's World of Mathematics, Disconnected Graph

Eric Weisstein's World of Mathematics, Quartic Graph

FORMULA

A033483 = A033301 - A006820 = Euler_transformation(A006820) - A006820.

a(n) = A068933(n, 4). - Jason Kimberley, Sep 27 2009 and Jan 08 2011

CROSSREFS

4-regular simple graphs: A006820 (connected), this sequence (disconnected), A033301 (not necessarily connected). - Jason Kimberley, Jan 08 2011

Disconnected regular simple graphs: A068932 (any degree), A068933 (triangular array), specified degree k: A165652 (k=2), A165653 (k=3), this sequence (k=4), A165655 (k=5), A165656 (k=6), A165877 (k=7), A165878 (k=8), A185293 (k=9), A185203 (k=10), A185213 (k=11).

Disconnected 4-regular simple graphs with girth at least g: this sequence (g=3), A185244 (g=4), A185245 (g=5), A185246 (g=6).

Sequence in context: A244278 A190343 A185043 * A130522 A006219 A009268

Adjacent sequences:  A033480 A033481 A033482 * A033484 A033485 A033486

KEYWORD

nonn,nice,hard,more

AUTHOR

R. C. Read (rcread(AT)math.uwaterloo.ca)

EXTENSIONS

3 more terms from Martin Fuller, Dec 04 2006

Terms a(19)-a(24) from Jason Kimberley, Sep 27 2009

Comment updated, and new terms a(25) and a(26) appended by Jason Kimberley, Dec 30 2010

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy .

Last modified September 21 15:13 EDT 2017. Contains 292300 sequences.