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 A367279 #11 Nov 12 2023 02:12:17 %S A367279 4,16,156,788,2880,6468,15800,27828,49936,78732,134656,173396,286676, %T A367279 373004,495300,659556,938328,1086108,1525216,1727060,2187912,2724272, %U A367279 3468932,3730780,4781740,5611000,6549252,7404820,9272476,9645308,12278824,13302464,15300332,17565324,19475404,20973584 %N A367279 Place n equally spaced points on each side of a square, and join each of these points by a chord to the 3*n new points on the other three sides: sequence gives number of edges in the resulting planar graph. %C A367279 See A367276 for further information. See A367276 and A367278 for images of the square. %F A367279 a(n) = A367276(n) + A367278(n) - 1 (Euler). %Y A367279 Cf. A367276 (vertices), A367277 (interior vertices), A367278 (regions). %K A367279 nonn %O A367279 0,1 %A A367279 _Scott R. Shannon_, Nov 11 2023