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 A261058 #8 Apr 25 2018 19:28:41 %S A261058 1,3,10,32,106,357,1222,4230,14770,51918,183472,651191,2319626, %T A261058 8288135,29691760,106611596,383565754,1382423748,4990274016, %U A261058 18039252192,65292492328,236595647526,858231115540,3116138603103,11324267454946,41186435585589,149907159998452,545997804435897 %N A261058 Column k=1 of A213221. %H A261058 Donatella Merlini, Massimo Nocentini, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL21/Merlini/merlini5.html">Algebraic Generating Functions for Languages Avoiding Riordan Patterns</a>, Journal of Integer Sequences, Vol. 21 (2018), Article 18.1.3. %F A261058 Conjecture: n*a(n) +(n-3)*a(n-1) +3*(-7*n+10)*a(n-2) +3*(n-1)*a(n-3) +40*(n-2)*a(n-4) +2*(-2*n+3)*a(n-5) +10*(-2*n+5)*a(n-6)=0. %Y A261058 Cf. A213221. %K A261058 nonn %O A261058 1,2 %A A261058 _R. J. Mathar_, Aug 08 2015