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 A075204 #12 Dec 05 2014 03:04:23 %S A075204 0,0,0,0,0,0,3,22,80,323,338,3322,3178,13590,43045,76881,48781,551137, %T A075204 93592,2190553,3163376,3542450,1065943,39341178,31694933 %N A075204 Number of polyominoes with n cells that tile the plane isohedrally but not by translation or by 180-degree rotation (Conway criterion). %C A075204 A tiling is isohedral if the symmetries of the tiling act transitively on the tiles; a shape is anisohedral if it tiles the plane, but not isohedrally. %D A075204 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4. %H A075204 Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyomino tiling</a> %Y A075204 Cf. A054359, A075198, A075199, A075200, A075201, A075202, A075203, A075205, A075206, A075213, A075222. %K A075204 hard,nonn %O A075204 1,7 %A A075204 _Joseph Myers_, Sep 08 2002 %E A075204 More terms from _Joseph Myers_, Nov 04 2003 %E A075204 a(24) and a(25) from _Joseph Myers_, Nov 17 2010