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 A075223 #11 Dec 05 2014 02:44:27 %S A075223 1,1,1,3,4,12,23,66,133,316,514,1987,2398,6073,12628,29918,26211, %T A075223 108778,95348,375045,498168,780434,843319,4981628,3691212,7357764, %U A075223 13169722,33461765,22372303,117437124 %N A075223 Number of polyiamonds with n cells that tile the plane isohedrally. %C A075223 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 A075223 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4. %H A075223 Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyiamond tiling</a> %Y A075223 Cf. A071332, A075216, A075217, A075218, A075219, A075220, A075221, A075222, A075224, A075205, A075214. %K A075223 hard,nonn %O A075223 1,4 %A A075223 _Joseph Myers_, Sep 08 2002 %E A075223 More terms from _Joseph Myers_, Nov 11 2003 %E A075223 a(29) and a(30) from _Joseph Myers_, Nov 21 2010