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 A197551 #9 Dec 05 2014 03:00:07 %S A197551 1,1,4,10,37,147,637,2823,13020,60649,286549,1364667,6547108,31586568 %N A197551 Number of free poly-IH18-tiles (holes allowed) with n cells. %C A197551 Equivalently, polyhexes where two polyhexes are considered equivalent if and only if they are related by a translation, a rotation of order 3 or a reflection or glide reflection in a line perpendicular to the sides of the hexagons. %D A197551 Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4. %Y A197551 Cf. A000228, A001207, A006535, A057973, A197549, A197550, A197552, A197553, A197554. %K A197551 hard,nonn %O A197551 1,3 %A A197551 _Joseph Myers_, Oct 16 2011