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 A212553 #16 Jun 04 2012 23:38:32
%S A212553 3,15,126,1395,18678,289926,5090220,99466371,2138575590,50153137650,
%T A212553 1274013771300,34853264146350,1021795130252988,31964591332833900,
%U A212553 1062945070050997656,37447053359058465507,1393372283171378001030
%N A212553 Irreducible near matchings over 2n+1 vertices.
%H A212553 Takahisa Toda and Ivo Vigan, <a href="http://venus.cs.qc.cuny.edu/~ivigan/SeparatingFamilies.pdf">On Separating Convex Points with Lines</a>
%F A212553 a(n) = A000699(n+1)*(2*n+1)*(n+1)/(2*n).
%e A212553 a(1) corresponds to the 3-vertex graphs with edge sets {{1,2},{2,3}}, {{1,2},{1,3}} and {{1,3},{2,3}} respectively.
%e A212553 a(2) corresponds to the 5-vertex graphs with edge sets {{1,2},{2,4},{3,5}}, {{1,4},{2,3},{2,5}} ...
%o A212553 (PARI)
%o A212553 A000699(n)={my(A); A=O(x); for(i=1, n, A=x+A*(2*x*A'-A)); polcoeff(A, n)}
%o A212553 a(n)=A000699(n+1)*(2*n+1)*(n+1)/(2*n);
%o A212553 vector(66,n,a(n))
%o A212553 /* _Joerg Arndt_, May 27 2012 */
%Y A212553 Cf. A000699, A200142.
%K A212553 nonn
%O A212553 1,1
%A A212553 _Ivo Vigan_, May 20 2012