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 A185134 Number of, not necessarily connected, 3-regular simple graphs on 2n vertices with girth exactly 4. 12
 0, 0, 0, 1, 2, 5, 21, 103, 752, 7385, 91939, 1345933, 22170664, 401399440, 7887389438, 166897766824, 3781593764772 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS Table of n, a(n) for n=0..16. Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth exactly g FORMULA a(n) = A185334(n) - A185335(n). a(n) = A006924(n) + A185034(n). CROSSREFS Not necessarily connected k-regular simple graphs girth exactly 4: A198314 (any k), A185644 (triangle); fixed k: A026797 (k=2), this sequence (k=3), A185144 (k=4). Not necessarily connected 3-regular simple graphs on 2n vertices with girth exactly g: A185130 (triangle); fixed g: A185133 (g=3), this sequence (g=4), A185135 (g=5), A185136 (g=6). Sequence in context: A115087 A008981 A008982 * A347497 A130471 A002628 Adjacent sequences: A185131 A185132 A185133 * A185135 A185136 A185137 KEYWORD nonn,hard,more AUTHOR Jason Kimberley, Mar 21 2012 STATUS approved

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Last modified November 29 19:11 EST 2023. Contains 367447 sequences. (Running on oeis4.)