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 A054359 #9 Mar 30 2012 17:28:41 %S A054359 1,1,2,5,12,35,104,343,1050,3070,6620,23449,38669,109104,279583, %T A054359 546893,827035,3057332,3381124,12126683,21921192,37008138,53327764, %U A054359 220908809,271293803 %N A054359 Number of polyominoes with n cells that tile the plane. %D A054359 Glenn C. Rhoads (rhoads(AT)paul.rutgers.edu), rec.puzzles, Feb 17 2000. %H A054359 Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyomino tiling</a> %Y A054359 Cf. A000105, A054360. %K A054359 nonn,hard %O A054359 1,3 %A A054359 Joe Keane (jgk(AT)jgk.org) %E A054359 Corrected and extended by _Joseph Myers_, May 05 2002 %E A054359 More terms from _Joseph Myers_, Nov 04 2003 %E A054359 a(24) and a(25) from _Joseph Myers_, Nov 17 2010