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.

A167653 Number of reduced words of length n in Coxeter group on 8 generators S_i with relations (S_i)^2 = (S_i S_j)^15 = I.

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%I A167653 #10 Nov 24 2016 11:02:08
%S A167653 1,8,56,392,2744,19208,134456,941192,6588344,46118408,322828856,
%T A167653 2259801992,15818613944,110730297608,775112083256,5425784582764,
%U A167653 37980492079152,265863444552720,1861044111859632,13027308782951568
%N A167653 Number of reduced words of length n in Coxeter group on 8 generators S_i with relations (S_i)^2 = (S_i S_j)^15 = I.
%C A167653 The initial terms coincide with those of A003950, although the two sequences are eventually different.
%C A167653 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167653 G. C. Greubel, <a href="/A167653/b167653.txt">Table of n, a(n) for n = 0..500</a>
%H A167653 <a href="/index/Rec#order_15">Index entries for linear recurrences with constant coefficients</a>, signature (6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, -21).
%F A167653 G.f.: (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)/(21*t^15 - 6*t^14 - 6*t^13 - 6*t^12 - 6*t^11 - 6*t^10 - 6*t^9 - 6*t^8 - 6*t^7 - 6*t^6 - 6*t^5 - 6*t^4 - 6*t^3 - 6*t^2 - 6*t + 1).
%t A167653 CoefficientList[Series[(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)/(21*t^15 - 6*t^14 - 6*t^13 - 6*t^12 - 6*t^11 - 6*t^10 - 6*t^9 - 6*t^8 - 6*t^7 - 6*t^6 - 6*t^5 - 6*t^4 - 6*t^3 - 6*t^2 - 6*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, Jun 18 2016 *)
%K A167653 nonn
%O A167653 0,2
%A A167653 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009