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 A217753 #11 Sep 15 2013 00:56:12 %S A217753 0,0,0,0,1,2,5,7,14,18,30,35,55,62,90 %N A217753 Number of noncongruent polygonal regions with finite area in the exterior of a regular n-gon with all diagonals drawn. %e A217753 a(7) = 1 since the 35 exterior regions of the regular heptagon built by all diagonals consist of one noncongruent polygon, i.e., 1 triangle (7 times), and three different noncongruent regions with infinite area (two 7 times, one 14 times). %e A217753 a(8) = 2 since the 64 exterior regions of the regular octagon built by all diagonals consist of two different noncongruent polygons, i.e., 2 triangles (one 8 times, one 16 times), and three different noncongruent regions with infinite area (one 8 times, two 16 times). %e A217753 a(9) = 5 since the 117 exterior regions of the regular 9-gon (nonagon) built by all diagonals consist of five different noncongruent polygons, i.e., 3 triangles (one 9 times, two 18 times) and 2 quadrilaterals (each 9 times), and four different noncongruent regions with infinite area (two 9 times, two 18 times). %Y A217753 Cf. A004526, A187781, A217745, A217746, A217748, A217754. %K A217753 nonn %O A217753 3,6 %A A217753 _Martin Renner_, Mar 23 2013