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 A194091 #47 May 24 2021 23:30:55 %S A194091 1,1,3,14,82,554,4132,33154,281459,2499523 %N A194091 The number of labeled biconnected squaregraphs with perimeter 2*n. %C A194091 Conjecture: The next terms are 23031395, 218862682, 2134993642, 21301755122, 216752986922, 2243977451994, 23590001630055, 251411579942151. - _Michael D. Weiner_, Apr 07 2016 %C A194091 Conjecture: a(n) is also the number of connected 3-noncrossing perfect matchings on [2n] (compare to A005700). - _Michael D. Weiner_, Jun 09 2017 %H A194091 Don Knuth, <a href="http://www-cs-faculty.stanford.edu/~knuth/programs/squaregraph.w">squaregraph.w</a> (CWEB program). %H A194091 Robert Scherer, <a href="https://www.math.ucdavis.edu/~tdenena/dissertations/202101_Scherer_Dissertation.pdf">Topics in Number Theory and Combinatorics</a>, Ph. D. Dissertation, Univ. of California Davis (2021). %F A194091 G.f.: A(x) satisfies A(x*T(x)^2) = T(x)-1 where T(x) is the o.g.f. for A005700 (conjectured). - _Michael D. Weiner_, Jun 09 2017 %e A194091 [See A194090 for the definition of "labeled squaregraph".] For n=4 the a(4)=14 labeled biconnected squaregraphs of perimeter 8 are the straight tromino (with 4 labelings), the L tromino (with 8), and the square tetromino (with 2). %o A194091 (CWEB) (see Knuth link). %Y A194091 Cf. A194088, A194089, A194090, A194092, A194093. %K A194091 nonn,hard,more %O A194091 1,3 %A A194091 _Don Knuth_, Aug 15 2011 %E A194091 Conjectured terms removed from data by _Michael D. Weiner_, Aug 03 2017