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A198314 Number of, not necessarily connected, regular simple graphs on n vertices with girth exactly 4. 9

%I

%S 0,0,0,0,1,0,1,0,4,1,8,3,37,33,335,1610,17985,193911,2867313,32674066,

%T 1581626531,6705889862

%N Number of, not necessarily connected, regular simple graphs on n 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) = A186744(n) + A210714(n).

%F a(n) = A185314(n) - A185315(n).

%Y Not necessarily connected k-regular simple graphs girth exactly 4: this sequence (any k), A185644 (triangle); fixed k: A026797 (k=2), A185134 (k=3), A185144 (k=4).

%Y Not necessarily connected regular simple graphs girth exactly g: A198313 (g=3), this sequence (g=4), A198315 (g=5), A198316 (g=6), A198317 (g=7), A198318 (g=8).

%K nonn,more,hard

%O 0,9

%A _Jason Kimberley_, Dec 12 2012

%E a(10) corrected from 9 to 8 by _Jason Kimberley_, Feb 22 2013

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Last modified February 27 15:59 EST 2020. Contains 332307 sequences. (Running on oeis4.)