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 A194089 #10 Jul 22 2025 12:32:18 %S A194089 1,3,12,57,295,1615,9190,53811,322078 %N A194089 The number of labeled biconnected squaregraphs that contain n squares. %D A194089 see A194088 %H A194089 Don Knuth, <a href="http://www-cs-faculty.stanford.edu/~knuth/programs/squaregraph.w">squaregraph.w</a> (CWEB program). %e A194089 A biconnected squaregraph is "labeled" if one of the edges on its periphery is given an orientation. The a(2)=3 examples with n=2 are the domino together with two possible ways to orient one of the edges on its "long" side, and one way to orient an edge on the short side. If a squaregraph has m automorphisms and perimeter 2p, the number of different ways to label it is 4p/m. %o A194089 (CWEB) (see Knuth link). %Y A194089 cf. A194088, A194090, A194091, A194092, A194093. %K A194089 nonn,hard,more %O A194089 1,2 %A A194089 _Don Knuth_, Aug 15 2011