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 A168751 #15 Oct 28 2018 17:52:02
%S A168751 1,26,650,16250,406250,10156250,253906250,6347656250,158691406250,
%T A168751 3967285156250,99182128906250,2479553222656250,61988830566406250,
%U A168751 1549720764160156250,38743019104003906250,968575477600097656250
%N A168751 Number of reduced words of length n in Coxeter group on 26 generators S_i with relations (S_i)^2 = (S_i S_j)^18 = I.
%C A168751 The initial terms coincide with those of A170745, although the two sequences are eventually different.
%C A168751 First disagreement at index 18: a(18) = 15133991837501525878905925, A170745(18) = 15133991837501525878906250. - _Klaus Brockhaus_, Mar 26 2011
%C A168751 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168751 G. C. Greubel, <a href="/A168751/b168751.txt">Table of n, a(n) for n = 0..500</a>
%H A168751 <a href="/index/Rec#order_18">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, -300).
%F A168751 G.f.: (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^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 A168751 CoefficientList[Series[(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^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, 0, 50}], t] (* _G. C. Greubel_, Aug 10 2016 *)
%t A168751 coxG[{18,300,-24}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Oct 28 2018 *)
%Y A168751 Cf. A170745 (G.f.: (1+x)/(1-25*x)).
%K A168751 nonn,easy
%O A168751 0,2
%A A168751 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009