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.

A167075 Number of reduced words of length n in Coxeter group on 22 generators S_i with relations (S_i)^2 = (S_i S_j)^13 = I.

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%I A167075 #12 Dec 10 2017 18:19:00
%S A167075 1,22,462,9702,203742,4278582,89850222,1886854662,39623947902,
%T A167075 832102905942,17474161024782,366957381520422,7706105011928862,
%U A167075 161828205250505871,3398392310260618440,71366238515472885600
%N A167075 Number of reduced words of length n in Coxeter group on 22 generators S_i with relations (S_i)^2 = (S_i S_j)^13 = I.
%C A167075 The initial terms coincide with those of A170741, although the two sequences are eventually different.
%C A167075 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167075 G. C. Greubel, <a href="/A167075/b167075.txt">Table of n, a(n) for n = 0..500</a>
%H A167075 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, -210).
%F A167075 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)/(210*t^13 - 20*t^12 - 20*t^11 - 20*t^10 - 20*t^9 - 20*t^8 - 20*t^7 - 20*t^6 - 20*t^5 - 20*t^4 - 20*t^3 - 20*t^2 - 20*t + 1).
%t A167075 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)/(210*t^13 - 20*t^12 - 20*t^11 - 20*t^10 - 20*t^9 - 20*t^8 - 20*t^7 - 20*t^6 - 20*t^5 - 20*t^4 - 20*t^3 - 20*t^2 - 20*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, May 31 2016 *)
%t A167075 coxG[{13,210,-20}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Dec 10 2017 *)
%K A167075 nonn
%O A167075 0,2
%A A167075 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009