This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A185144 #25 Feb 22 2013 10:47:04 %S A185144 0,0,0,0,0,0,0,0,1,0,2,2,12,31,220,1606,16829,193900,2452820,32670331, %T A185144 456028487,6636066126,100135577863,1582718910743 %N A185144 Number of not necessarily connected 4-regular simple graphs on n vertices with girth exactly 4. %H A185144 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 A185144 a(n) = A184944(n) + A185044(n) = A185140(n,4). %Y A185144 Not necessarily connected k-regular simple graphs girth exactly 4: A198314 (any k), A185644 (triangle); fixed k: A026797 (k=2), A185134 (k=3), this sequence (k=4). %Y A185144 A185143 (g=3), A185144 (g=4). %Y A185144 Not necessarily connected 4-regular simple graphs with girth exactly g: A185140 (triangle); fixed g: A185143 (g=3), this sequence (g=4). %K A185144 nonn,hard,more %O A185144 0,11 %A A185144 _Jason Kimberley_, Nov 04 2011 %E A185144 Corrected by _Jason Kimberley_, Jan 03 2013