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 A033483 Number of disconnected 4-valent (or quartic) graphs with n nodes. 17
 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, 31510542635443, 464047929509794, 7143991172244290, 114749135506381940, 1919658575933845129, 33393712487076999918, 603152722419661386031 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,13 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 a(n) = A033301(n) - A006820(n) = Euler_transformation(A006820) - A006820. a(n) = A068933(n, 4). - Jason Kimberley, Sep 27 2009 and Jan 08 2011 MATHEMATICA A006820 = Cases[Import["https://oeis.org/A006820/b006820.txt", "Table"], {_, _}][[All, 2]]; (* EulerTransform is defined in A005195 *) EulerTransform[Rest @ A006820] - A006820 (* Jean-François Alcover, Jan 21 2020, updated Mar 17 2020 *) 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 A353406 Adjacent sequences: A033480 A033481 A033482 * A033484 A033485 A033486 KEYWORD nonn,nice,hard AUTHOR R. C. Read (rcread(AT)math.uwaterloo.ca) EXTENSIONS Terms a(16)-a(18) from Martin Fuller, Dec 04 2006 Terms a(19)-a(26) from Jason Kimberley, Sep 27 2009 and Dec 30 2010 Terms a(27)-a(33), due to the extension of A006820 by Andrew Howroyd, from Jason Kimberley, Mar 12 2020 STATUS approved

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Last modified December 6 01:03 EST 2022. Contains 358594 sequences. (Running on oeis4.)