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 A320422 #18 Jan 08 2019 18:48:27 %S A320422 6,25,50,145,224,497,684,1281,1650,2713,3406,5223,6300,9137,10744, %T A320422 14779,17214,23161,26250,34277,38456,49105,54500,68225,75114,92457, %U A320422 101094,122371 %N A320422 The number of tiles inside a regular n-gon created by diagonals that run from each of the n vertices to the n-2 midpoints of opposite edges. %C A320422 Sequence proposed by Thomas Young: draw the regular n-gon and construct n*(n-2) diagonals that run from each of the n vertices to the n-2 points in the middle of the opposite edges, where opposite edges are those not adjacent to the vertex. Count the non-overlapping polygons inside the n-gon which have sides that are sections of the diagonals or sections of the n-gon edges. %H A320422 R. J. Mathar, <a href="/A320422/a320422.pdf">Tile count in the interior of regular n-gons dissected by medians</a> %H A320422 <a href="/index/Pol#Poonen">Index to sequences on drawing diagonals in regular polygons</a> %F A320422 Conjecture: a(2n+1) = n*(2*n+1)*(4*n^2-3*n+5)/3. - Thomas Young (tyoung(AT)district16.org), Jan 05 2019 %Y A320422 Cf. A165217, A320431. %K A320422 nonn,more %O A320422 3,1 %A A320422 _R. J. Mathar_, Jan 08 2019