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%I #12 May 01 2014 02:37:07
%S 0,0,0,1,2,5,21,103,752,7385,91939,1345933,22170664,401399440,
%T 7887389438,166897766824,3781593764772
%N Number of, not necessarily connected, 3-regular simple graphs on 2n vertices with girth exactly 4.
%H Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/E_k-reg_girth_eq_g_index">Index of sequences counting not necessarily connected k-regular simple graphs with girth exactly g</a>
%F a(n) = A185334(n) - A185335(n).
%F a(n) = A006924(n) + A185034(n).
%Y 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).
%Y 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).
%K nonn,hard,more
%O 0,5
%A _Jason Kimberley_, Mar 21 2012
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