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 A369177 #12 Jan 22 2024 08:58:20 %S A369177 6,24,66,152,318,576,998,1608,2474,3600,5162,7100,9670,12772,16546, %T A369177 21036,26622,33024,40814,49716,60006,71560,85158,100264,117626,136780, %U A369177 158358,182080,209106,238312,271314,307304,346866,389488,436286,486444,542026,601436,665814,734504,809882,889544 %N A369177 Number of edges in a graph of n adjacent rectangles in a row with all possible diagonals drawn, as in A306302, but without the rectangles' edges which are perpendicular to the row. %C A369177 See A369175 and A369176 for images of the graph. %F A369177 a(n) = A369175(n) + A369176(n) - 1 by Euler's formula. %Y A369177 Cf. A369175 (regions), A369176 (vertices), A369178 (k-gons), A306302, A331757, A290132, A368757. %K A369177 nonn %O A369177 1,1 %A A369177 _Scott R. Shannon_, Jan 15 2024