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 A051570 #7 Mar 28 2015 11:49:46 %S A051570 2,4,31,307,2,9,755,39302 %N A051570 Consider the problem of placing N queens on an n X n board so that each queen attacks precisely k others. Here k=3 and sequence gives number of different solutions when N takes its maximal value. %C A051570 I would also like to get the sequences that gives the maximal values of N. %D A051570 M. Gardner, The Last Recreations, Springer, 1997, p. 282. %Y A051570 Cf. A051567-A051571, A051754-A051759, A019654. %K A051570 nonn,nice,more %O A051570 3,1 %A A051570 _N. J. A. Sloane_ %E A051570 I am not certain this description is correct, nor how rigorous the results are.