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 A331207 #28 Feb 22 2020 15:43:57 %S A331207 0,4,7,10,13,12,15,18,17,20,23,22,25,28,24,27,30,29,32,35,31,34,37,36, %T A331207 39,42,38,41,44,43,40,43,46,45 %N A331207 Minimum number of matchsticks sufficient to form the edges of exactly n squares of any size >= 1. %H A331207 John King, <a href="/A331207/a331207_1.jpg">diagram for A331207 & A331208</a> %Y A331207 Cf. A027709, A078633, A331208. %K A331207 nonn,more %O A331207 0,2 %A A331207 _John King_, Jan 12 2020