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 A368755 #18 Feb 16 2025 08:34:06 %S A368755 0,2,18,64,186,380,838,1504,2242,4082,6266,8320,13010,17866,20218, %T A368755 31808,41390,50100,66530,82560,93446,123642,149398,171920,212166, %U A368755 249810,283678,340704,394882,428892,521406,594560,659382,764866,863154,954192,1086490,1212506,1326654,1498720,1660278 %N A368755 Number of regions in the hyperoctahedral (or cocktail party) graph of order n. %H A368755 Scott R. Shannon, <a href="/A368755/a368755.png">Image for n = 2</a>. %H A368755 Scott R. Shannon, <a href="/A368755/a368755_1.png">Image for n = 3</a>. %H A368755 Scott R. Shannon, <a href="/A368755/a368755_2.png">Image for n = 4</a>. %H A368755 Scott R. Shannon, <a href="/A368755/a368755_3.png">Image for n = 5</a>. %H A368755 Scott R. Shannon, <a href="/A368755/a368755_4.png">Image for n = 6</a>. %H A368755 Scott R. Shannon, <a href="/A368755/a368755_5.png">Image for n = 9</a>. %H A368755 Scott R. Shannon, <a href="/A368755/a368755_6.png">Image for n = 10</a>. %H A368755 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CocktailPartyGraph.html">Cocktail Party Graph</a>. %F A368755 a(n) = A368757(n) - A368756(n) + 1 by Euler's formula. %Y A368755 Cf. A368756 (vertices), A368757 (edges), A368758 (k-gons), A129348, A193130, A282010. %K A368755 nonn %O A368755 1,2 %A A368755 _Scott R. Shannon_, Jan 04 2024