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 A210507 #11 Mar 24 2017 00:47:54 %S A210507 1,10,111,1468,22940,416250,8626660,201349672,5230931454,149783426470, %T A210507 4688281021490,159284662406460,5838769123729984,229711022253150382, %U A210507 9655348958575618320,431845990498159342000,20479127764425617465660,1026429489947790074019978 %N A210507 Number of labeled graphs on [n] with unicyclic components containing a given edge. %C A210507 This gives the number of matroid bases that contain a given element (edge) of the bicircular matroid of K_n. %D A210507 O. Giménez, A. de Mier, M. Noy, On the Number of Bases of Bicircular Matroids, Ann. Comb. 9 (2005), no. 1, 35-45. %F A210507 a(n) = 2*b(n)/(n-1), where b(n) is seq A137916. %e A210507 a(4)=10 means that 10 (of the 15) labeled unicyclic graphs on 4 vertices contain a given edge. %Y A210507 Cf. A137916. %K A210507 nonn %O A210507 3,2 %A A210507 _Gary Gordon_, Jan 25 2013