A359986 Number of quasi series-parallel matroids on [n].

1, 2, 5, 16, 67, 374, 2795, 27472, 343129, 5242178, 94775045, 1976279584, 46619596363, 1225918376726, 35526110971595, 1124201803439968, 38555828073355441, 1424165085382532162, 56356111920073052165, 2378150844047351691376, 106590791633357076443347

Offset: 0

Author

Andrew Howroyd, Mar 08 2023

Keywords

• nonn

Comments

A quasi series-parallel matroid is a collection of series-parallel matroids. See the Ferroni/Larson reference for a precise definition.

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..200
• Luis Ferroni and Matt Larson, Kazhdan-Lusztig polynomials of braid matroids, arXiv:2303.02253 [math.CO], 2023.

Crossrefs

Row sums of A359985.

Programs

PARI

seq(n)=Vec(serlaplace( exp(2*x + intformal(serreverse(2*log(1 + x + O(x^n)) - x))) ))

PARI

seq(n) = Vec(serlaplace( exp(2*x + intformal(-x + 2*serreverse(1 + 2*x - exp(x + O(x^n))))) ))