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%I #4 Mar 08 2023 23:17:22
%S 1,2,5,16,67,374,2795,27472,343129,5242178,94775045,1976279584,
%T 46619596363,1225918376726,35526110971595,1124201803439968,
%U 38555828073355441,1424165085382532162,56356111920073052165,2378150844047351691376,106590791633357076443347
%N Number of quasi series-parallel matroids on [n].
%C A quasi series-parallel matroid is a collection of series-parallel matroids. See the Ferroni/Larson reference for a precise definition.
%H Luis Ferroni and Matt Larson, <a href="https://arxiv.org/abs/2303.02253">Kazhdan-Lusztig polynomials of braid matroids</a>, arXiv:2303.02253 [math.CO], 2023.
%o (PARI) seq(n)=Vec(serlaplace( exp(2*x + intformal(serreverse(2*log(1 + x + O(x^n)) - x))) ))
%o (PARI) seq(n) = Vec(serlaplace( exp(2*x + intformal(-x + 2*serreverse(1 + 2*x - exp(x + O(x^n))))) ))
%Y Row sums of A359985.
%K nonn
%O 0,2
%A _Andrew Howroyd_, Mar 08 2023
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