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 A333031 #8 May 02 2020 05:02:24 %S A333031 3,10,58,183,408,777,1323,2142,3276,4773,6717,9264,12507,16554,21351, %T A333031 27090,34047,42318,52008,63453,76566,91371,108249,127608,149487, %U A333031 173982,201072,231225,265002,302487,343857,389856,440175,494670,553611,617610,687477,763320 %N A333031 Number of vertices in an equilateral triangle "frame" of size n (see Comments in A328526 for definition). %C A333031 For n<=3 the terms equal A274585(n). See A328526 for images of the triangular frame. %H A333031 Lars Blomberg, <a href="/A333031/b333031.txt">Table of n, a(n) for n = 1..65</a> %Y A333031 Cf. A328526 (regions), A333030 (edges), A333032 (3-gons), A333033 (4-gons), A331776 (square frame), A274586 (filled triangle). %K A333031 nonn %O A333031 1,1 %A A333031 _Scott R. Shannon_ and _N. J. A. Sloane_, Mar 05 2020 %E A333031 a(12) and beyond from _Lars Blomberg_, May 01 2020