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 A089454 #4 Apr 07 2015 10:48:39
%S A089454 0,0,0,0,0,0,0,0,0,0,4,41,346,2384,14560,81863,433172,2192752,
%T A089454 10726252,51094203,238259280,1092053068,4934652298,22034767837,
%U A089454 97407519119,426916828181
%N A089454 Number of n-celled polyominoes with exactly 2 holes.
%H A089454 Tomás Oliveira e Silva, <a href="http://www.ieeta.pt/%7Etos/animals/a44.html">Animal enumerations on the {4,4} Euclidean tiling</a>
%Y A089454 Cf. A001419, A057418, A089455, A089456, A089457, A089458.
%K A089454 hard,nonn
%O A089454 1,11
%A A089454 _Joseph Myers_, Nov 04 2003