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 A129551 #7 May 26 2013 15:14:22 %S A129551 0,0,0,0,0,0,4,44,280,1304,12452,105012,977664,9239816,90776620, %T A129551 897446092 %N A129551 Number of ways to place n+2 queens and 2 pawns on an n X n board so that no two queens attack each other. %H A129551 R. D. Chatham, <a href="http://people.moreheadstate.edu/fs/d.chatham/n+kqueens.html">The N+k Queens Problem Page</a>. %H A129551 R. D. Chatham, M. Doyle, G. H. Fricke, J. Reitmann, R. D. Skaggs and M. Wolff, <a href="http://people.moreheadstate.edu/fs/d.chatham/QueensSep2.pdf">Independence and Domination Separation in Chessboard Graphs</a>, J. Combin. Math. Combin. Comput. 68 (2009), 3-17. %e A129551 a(4)=0 because when 6 queens are placed on a 4 X 4 board, at least two queens will be adjacent and therefore mutually attacking. %Y A129551 Cf. A000170, A129552. %K A129551 more,nonn %O A129551 1,7 %A A129551 R. Douglas Chatham (d.chatham(AT)moreheadstate.edu), Apr 20 2007