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 A161859 #9 Mar 21 2025 16:31:28
%S A161859 1,13,90,442,1728,5720,16653,43745,105586,237354,502113,1007773,
%T A161859 1931631,3554747,6308719,10837683,18078554,29362618,46541560,72140848,
%U A161859 109543070,163203326,238898101,344008185,487835165,681949801,940569228,1280958420,1723849738,2293872698,3019984381
%N A161859 Number of reduced words of length n in the Weyl group B_13.
%C A161859 Computed with MAGMA using commands similar to those used to compute A161409.
%D A161859 J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.
%D A161859 N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)
%H A161859 Andrew Howroyd, <a href="/A161859/b161859.txt">Table of n, a(n) for n = 0..169</a>
%F A161859 G.f. for B_m is the polynomial Prod_{k=1..m}(1-x^(2k))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A128084.
%Y A161859 Row n=13 of A128084.
%K A161859 nonn,fini,full
%O A161859 0,2
%A A161859 _John Cannon_ and _N. J. A. Sloane_, Nov 30 2009