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 A089457 #4 Apr 07 2015 10:48:39
%S A089457 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,21,573,9140,105417,982767,
%T A089457 7919375,57387444
%N A089457 Number of n-celled polyominoes with exactly 5 holes.
%H A089457 Tomás Oliveira e Silva, <a href="http://www.ieeta.pt/%7Etos/animals/a44.html">Animal enumerations on the {4,4} Euclidean tiling</a>
%Y A089457 Cf. A001419, A057418, A089454, A089455, A089456, A089458.
%K A089457 hard,nonn
%O A089457 1,20
%A A089457 _Joseph Myers_, Nov 04 2003