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 A075211 #11 Dec 05 2014 02:41:00 %S A075211 1,1,3,7,21,75,256,929,3090,9235,21216,80463,138623,423595,1160355, %T A075211 2456117,4272856,15986299,21709209,75452662,156068738 %N A075211 Number of polyhexes with n cells that tile the plane by 180-degree rotation (Conway criterion). %D A075211 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4. %H A075211 Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyhex tiling</a> %Y A075211 Cf. A070766, A075207, A075208, A075209, A075210, A075212, A075213, A075214, A075215, A075202, A075220. %K A075211 hard,nonn %O A075211 1,3 %A A075211 _Joseph Myers_, Sep 08 2002 %E A075211 More terms from _Joseph Myers_, Nov 08 2003 %E A075211 a(20) and a(21) from _Joseph Myers_, Nov 21 2010