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 A168847 #10 Jun 25 2017 10:02:29
%S A168847 1,26,650,16250,406250,10156250,253906250,6347656250,158691406250,
%T A168847 3967285156250,99182128906250,2479553222656250,61988830566406250,
%U A168847 1549720764160156250,38743019104003906250,968575477600097656250
%N A168847 Number of reduced words of length n in Coxeter group on 26 generators S_i with relations (S_i)^2 = (S_i S_j)^20 = I.
%C A168847 The initial terms coincide with those of A170745, although the two sequences are eventually different.
%C A168847 First disagreement at index 20: a(20) = 9458744898438453674316405925, A170745(20) = 9458744898438453674316406250. - Klaus Brockhaus, Apr 02 2011
%C A168847 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168847 <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, -300).
%F A168847 G.f.: (t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 2*t^10 + 2*t^9 + 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(300*t^20 - 24*t^19 - 24*t^18 - 24*t^17 - 24*t^16 - 24*t^15 - 24*t^14 - 24*t^13 - 24*t^12 - 24*t^11 - 24*t^10 - 24*t^9 - 24*t^8 - 24*t^7 - 24*t^6 - 24*t^5 - 24*t^4 - 24*t^3 - 24*t^2 - 24*t + 1).
%t A168847 coxG[{20,300,-24}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Jun 25 2017 *)
%Y A168847 Cf. A170745 (G.f.: (1+x)/(1-25*x)).
%K A168847 nonn
%O A168847 0,2
%A A168847 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009