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 A143886 #8 Oct 21 2014 03:41:51 %S A143886 1,2,15,267,9450,577785,58537749,9751519234,2673230750387, %T A143886 1220300742842014 %N A143886 Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard. %Y A143886 Cf. A143870, A143875, A143881. %Y A143886 Cf. A143887, A143888, A143889, A143890, A143891, A143892, A143893. %K A143886 nonn,more,hard %O A143886 0,2 %A A143886 _R. H. Hardin_, Sep 04 2008