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 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 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

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Last modified October 23 14:29 EDT 2019. Contains 328345 sequences. (Running on oeis4.)