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.

A167694 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^15 = I.

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%I A167694 #10 Nov 24 2016 11:07:36
%S A167694 1,23,506,11132,244904,5387888,118533536,2607737792,57370231424,
%T A167694 1262145091328,27767192009216,610878224202752,13439320932460544,
%U A167694 295665060514131968,6504631331310903296,143101889288839872259
%N A167694 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^15 = I.
%C A167694 The initial terms coincide with those of A170742, although the two sequences are eventually different.
%C A167694 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167694 G. C. Greubel, <a href="/A167694/b167694.txt">Table of n, a(n) for n = 0..500</a>
%H A167694 <a href="/index/Rec#order_15">Index entries for linear recurrences with constant coefficients</a>, signature (21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, -231).
%F A167694 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)/(231*t^15 - 21*t^14 - 21*t^13 - 21*t^12 - 21*t^11 - 21*t^10 - 21*t^9 - 21*t^8 - 21*t^7 - 21*t^6 - 21*t^5 - 21*t^4 - 21*t^3 - 21*t^2 - 21*t + 1).
%t A167694 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)/(231*t^15 - 21*t^14 - 21*t^13 - 21*t^12 - 21*t^11 - 21*t^10 - 21*t^9 - 21*t^8 - 21*t^7 - 21*t^6 - 21*t^5 - 21*t^4 - 21*t^3 - 21*t^2 - 21*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, Jun 20 2016 *)
%K A167694 nonn
%O A167694 0,2
%A A167694 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009