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 A051571 #6 Mar 28 2015 11:50:11 %S A051571 0,0,0,1,3,40,615,16573 %N A051571 Consider problem of placing N queens on an n X n board so that each queen attacks precisely k others. Here k=4 and sequence gives number of different solutions when N takes its maximal value. %D A051571 M. Gardner, The Last Recreations, Springer, 1997, p. 282. %Y A051571 Cf. A051567-A051570, A051754-A051759, A019654. %K A051571 nonn,more %O A051571 3,5 %A A051571 _N. J. A. Sloane_ %E A051571 Probably an incorrect version of A019654.