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 A189509 #11 Apr 21 2015 12:38:55 %S A189509 1,6,65,701,9324,138016,2325740,43448940,897020784,20241273264 %N A189509 Column 3 of triangle in A189507. %H A189509 Simona Grusea and Anthony Labarre, <a href="http://arxiv.org/abs/1104.3353">The distribution of cycles in breakpoint graphs of signed permutations</a>, arXiv:1104.3353v1 %Y A189509 Cf. A189507. %K A189509 nonn,more %O A189509 2,2 %A A189509 _N. J. A. Sloane_, Apr 23 2011 %E A189509 Added missing term for n=9, _Anthony Labarre_, Feb 14 2013