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 A289137 #8 Jul 03 2017 22:34:19 %S A289137 1,13,88,1025,11822,147003,1866907 %N A289137 Number of extended polydrafters with n cells, identifying mirror images. %C A289137 An extended polydrafter is a plane figure formed by joining congruent 30-60-90 triangles along edges and half hypotenuses, without the requirement for proper polydrafters that the cells lie on the polyiamond (triangle) grid. %H A289137 Bernd Karl Rennhak, <a href="http://www.logelium.de/Drafter/PolyDrafter_EN.htm">Logelium: Drafter</a> %e A289137 a(2)=13 because there are 6 proper didrafters and 7 more didrafters that do not conform to the polyiamond grid. %e A289137 See the Logelium link for diagrams. %Y A289137 Cf. A056842 (number of [proper] polydrafters with n cells); A217720 (number of one-sided polydrafters with n cells). %K A289137 nonn,more,hard %O A289137 1,2 %A A289137 _George Sicherman_, Jun 25 2017