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 A357198 #13 Sep 18 2022 12:37:28 %S A357198 6,18,54,114,198,306,438,594,774,942,1206,1422,1734,2034,2310,2706, %T A357198 3078,3474,3894,4242,4806,5298,5814,6186,6918,7506,8118,8706,9414, %U A357198 9978,10806,11538,12258,13074,13842,14562,15558,16434,17298,17970,19206,20082,21174,22122,23154,24306,25398,26286 %N A357198 Number of edges in a hexagon when n internal hexagons are drawn between the 6n points that divide each side into n+1 equal parts. %C A357198 Unlike similar dissections of the triangle and square, see A357008 and A357061, there is no obvious pattern for n values that yield hexagons with non-simple intersections; these n values begin 9, 11, 14, 19, 23, 27, 29, 32, 34, 35, 38, 39, 41, 43, ... . %F A357198 a(n) = A357196(n) + A357197(n) - 1 by Euler's formula. %F A357198 Conjecture: a(n) = 12*n^2 + 6 for hexagons that only contain simple intersections when cut by n internal hexagons. %Y A357198 Cf. A357196 (regions), A357197 (vertices), A330845, A357008 (triangle), A357061 (square). %K A357198 nonn %O A357198 0,1 %A A357198 _Scott R. Shannon_, Sep 17 2022