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 A333281 #22 May 29 2021 07:04:59 %S A333281 13,37,121,265,587,1019,1797,2823,4369,6257,9001,12289,16775,21905, %T A333281 28383,35901,45463,56119,69351,84167,101687,120869,143777,168873, %U A333281 198191,229771,266015,305379,350673,399035,454243,513619,579787,649899,727927,810907,903581 %N A333281 Column 2 of triangle in A288180. %C A333281 For the graphs defined in A331452 and A288187 only the counts for graphs that are one square wide have formulas for regions, edges, and vertices (see A306302, A331757, A331755). For width 2 there are six such sequences (A331766, A331765, A331763; A333279, A333280, A333281). It would be nice to have a formula for any one of them. %C A333281 See A333279 for illustrations. %H A333281 Lars Blomberg, <a href="/A333281/b333281.txt">Table of n, a(n) for n = 1..200</a> %H A333281 Hugo Pfoertner, <a href="/A288177/a288177.pdf">Illustrations of Chamber Complexes up to 5 X 5</a>. %Y A333281 Cf. A331452, A288187; A331766, A331765, A331763; A333279, A333280, A333281. %K A333281 nonn %O A333281 1,1 %A A333281 _Scott R. Shannon_ and _N. J. A. Sloane_, Mar 15 2020 %E A333281 a(10) and beyond from _Lars Blomberg_, May 23 2021