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 A161438 #5 Jul 19 2015 10:35:47
%S A161438 1,6,20,49,98,169,259,359,455,531,573,573,531,455,359,259,169,98,49,
%T A161438 20,6,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%U A161438 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N A161438 Number of reduced words of length n in the Weyl group A_6.
%C A161438 Computed with MAGMA using commands similar to those used to compute A161409.
%D A161438 J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.
%D A161438 N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche I.)
%F A161438 G.f. for A_m is the polynomial Prod_{k=1..m}(1-x^(k+1))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A008302.
%K A161438 nonn
%O A161438 0,2
%A A161438 _John Cannon_ and _N. J. A. Sloane_, Nov 30 2009