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%I #8 Apr 25 2018 19:28:41
%S 1,3,10,32,106,357,1222,4230,14770,51918,183472,651191,2319626,
%T 8288135,29691760,106611596,383565754,1382423748,4990274016,
%U 18039252192,65292492328,236595647526,858231115540,3116138603103,11324267454946,41186435585589,149907159998452,545997804435897
%N Column k=1 of A213221.
%H 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 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 Cf. A213221.
%K nonn
%O 1,2
%A _R. J. Mathar_, Aug 08 2015