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 A194093 #9 Mar 31 2012 10:22:49 %S A194093 1,1,0,1,0,3,0,12,2,55,22,278,182,1506,1378,8595,10040,51134,71814, %T A194093 314693,509200 %N A194093 The number of labeled biconnected squaregraphs with n vertices. %D A194093 See A194088 %H A194093 Don Knuth, <a href="http://www-cs-faculty.stanford.edu/~knuth/programs/squaregraph.w">squaregraph.w</a> (CWEB program). %e A194093 [See A194089 for the definition of "labeling".] For n=11 the P-pentomino can be labeled in 20 ways; the 5-cogwheel in only 2; hence a(11)=22. %e A194093 The values of a(1) and a(2) depend on whether or not one believes that %e A194093 the small complete graphs K_1 and K_2 respectively are biconnected. %o A194093 (CWEB) (see Knuth link). %Y A194093 Cf. A194088, A194089, A194090, A194091, A194092. %K A194093 nonn,hard,more %O A194093 1,6 %A A194093 _Don Knuth_, Aug 15 2011