cp's OEIS Frontend

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.

A167080 Number of reduced words of length n in Coxeter group on 27 generators S_i with relations (S_i)^2 = (S_i S_j)^13 = I.

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%I A167080 #10 Nov 24 2016 10:30:49
%S A167080 1,27,702,18252,474552,12338352,320797152,8340725952,216858874752,
%T A167080 5638330743552,146596599332352,3811511582641152,99099301148669952,
%U A167080 2576581829865418401,66991127576500869300,1741769316989022364875
%N A167080 Number of reduced words of length n in Coxeter group on 27 generators S_i with relations (S_i)^2 = (S_i S_j)^13 = I.
%C A167080 The initial terms coincide with those of A170746, although the two sequences are eventually different.
%C A167080 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167080 G. C. Greubel, <a href="/A167080/b167080.txt">Table of n, a(n) for n = 0..500</a>
%H A167080 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, -325).
%F A167080 G.f.: (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)/(325*t^13 - 25*t^12 - 25*t^11 - 25*t^10 - 25*t^9 - 25*t^8 - 25*t^7 - 25*t^6 - 25*t^5 - 25*t^4 - 25*t^3 - 25*t^2 - 25*t + 1).
%t A167080 CoefficientList[Series[(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)/(325*t^13 - 25*t^12 - 25*t^11 - 25*t^10 - 25*t^9 - 25*t^8 - 25*t^7 - 25*t^6 - 25*t^5 - 25*t^4 - 25*t^3 - 25*t^2 - 25*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, May 31 2016 *)
%K A167080 nonn
%O A167080 0,2
%A A167080 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009