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 A161900 #9 Mar 17 2025 22:16:10
%S A161900 1,22,252,2002,12396,63734,283107,1116236,3983485,13057330,39764011,
%T A161900 113533312,306173263,784654154,1920802566,4510960122,10201294213,
%U A161900 22286443124,47167714715,96947735390,193938666735,378324531180,720920510115,1344018408150,2454841642634
%N A161900 Number of reduced words of length n in the Weyl group B_22.
%C A161900 Computed with MAGMA using commands similar to those used to compute A161409.
%D A161900 J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.
%D A161900 N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)
%H A161900 Andrew Howroyd, <a href="/A161900/b161900.txt">Table of n, a(n) for n = 0..484</a>
%F A161900 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 A161900 Row n=22 of A128084.
%K A161900 nonn,fini,full
%O A161900 0,2
%A A161900 _John Cannon_ and _N. J. A. Sloane_, Nov 30 2009