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 A168883 #10 Apr 11 2022 17:16:37
%S A168883 1,14,182,2366,30758,399854,5198102,67575326,878479238,11420230094,
%T A168883 148462991222,1930018885886,25090245516518,326173191714734,
%U A168883 4240251492291542,55123269399790046,716602502197270598
%N A168883 Number of reduced words of length n in Coxeter group on 14 generators S_i with relations (S_i)^2 = (S_i S_j)^21 = I.
%C A168883 The initial terms coincide with those of A170733, although the two sequences are eventually different.
%C A168883 First disagreement at index 21: a(21) = 266069492848331192143123, A170733(21) = 266069492848331192143214. - Klaus Brockhaus, Apr 05 2011
%C A168883 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168883 <a href="/index/Rec#order_21">Index entries for linear recurrences with constant coefficients</a>, signature (12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, -78).
%F A168883 G.f.: (t^21 + 2*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)/(78*t^21 - 12*t^20 - 12*t^19 - 12*t^18 - 12*t^17 - 12*t^16 - 12*t^15 - 12*t^14 - 12*t^13 - 12*t^12 - 12*t^11 - 12*t^10 - 12*t^9 - 12*t^8 - 12*t^7 - 12*t^6 - 12*t^5 - 12*t^4 - 12*t^3 - 12*t^2 - 12*t + 1).
%t A168883 coxG[{21,78,-12}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Apr 11 2022 *)
%Y A168883 Cf. A170733 (G.f.: (1+x)/(1-13*x)).
%K A168883 nonn
%O A168883 0,2
%A A168883 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009