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 A116507 #3 May 10 2013 12:45:45
%S A116507 0,1,91,18943,12483601,28530385447,235529139302185,7183142489571818623
%N A116507 Number of singular n X n rational {0,1}-matrices with no zero rows or columns.
%F A116507 a(n) = A048291(n) - A055165(n).
%Y A116507 Cf. A000410, A116506, A116527, A116532.
%K A116507 more,nonn
%O A116507 1,3
%A A116507 _Vladeta Jovovic_, Apr 03 2006