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 A191101 #11 Mar 31 2012 10:29:18 %S A191101 6,18,43,72,145,210,364,432,768,938,1441,1680,2483,2448,4010,4480, %T A191101 6154,6798,9063,9000,12901,13962,17848,19152,24100,21450,31869,33824, %U A191101 41383,43758,52886,52920,66638,69958,82915,86760,102009 %N A191101 Number of regions in a complete but borderless regular polygon. %C A191101 A complete borderless polygon is one where each vertex is connected to every other vertex except for adjacent vertices. Adjacent vertices are not connected by edges. The result is a polygon interior. %F A191101 a(n) = A007678(n) - n. %Y A191101 Cf. A007678. %K A191101 nonn,easy %O A191101 5,1 %A A191101 _Stefan Hannie_, May 25 2011 %E A191101 a(8) onward corrected by _T. D. Noe_, Jun 02 2011