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 A161875 #19 Mar 23 2025 20:51:34
%S A161875 1,15,119,665,2939,10933,35580,103972,277950,689282,1602727,3523945,
%T A161875 7376794,14784390,28500705,53054703,95687255,167682425,286219155,
%U A161875 476896733,777117381,1240541355,1942863430,2989193690,4523359115,6739474341,9896158795,14333801669,20495294280
%N A161875 Number of reduced words of length n in the Weyl group B_15.
%C A161875 Computed with MAGMA using commands similar to those used to compute A161409.
%D A161875 J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.
%D A161875 N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)
%H A161875 Robert Israel, <a href="/A161875/b161875.txt">Table of n, a(n) for n = 0..225</a>
%F A161875 G.f. for B_m is the polynomial Product_{k=1..m}(1-x^(2k))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A128084.
%p A161875 G:= normal(mul((1-x^(2*k))/(1-x), k=1..15)):
%p A161875 seq(coeff(G, x, j), j=0..15^2); # _Robert Israel_, Nov 26 2017
%Y A161875 Row n=15 of A128084.
%K A161875 nonn,fini,full
%O A161875 0,2
%A A161875 _John Cannon_ and _N. J. A. Sloane_, Nov 30 2009
%E A161875 a(28) corrected by _Sean A. Irvine_, Mar 23 2025