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 A161977 #5 Jul 19 2015 10:24:00
%S A161977 1,31,495,5425,45879,319145,1900920,9965384,46909324,201295028,
%T A161977 796809245,2937251395,10161553364,33205476524,103050077489,
%U A161977 305131440111,865481871426,2359754902590,6203436293890,15765840836350,38828731002622
%N A161977 Number of reduced words of length n in the Weyl group B_31.
%C A161977 Computed with MAGMA using commands similar to those used to compute A161409.
%D A161977 J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.
%D A161977 N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)
%F A161977 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.
%K A161977 nonn
%O A161977 0,2
%A A161977 _John Cannon_ and _N. J. A. Sloane_, Nov 30 2009