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 A164634 #9 Feb 22 2024 13:33:16 %S A164634 1,21,420,8400,168000,3360000,67200000,1343999790,26879991600, %T A164634 537599748210,10751993288400,215039832252000,4300795974720000, %U A164634 86015906088000000,1720317853632043890,34406351710082593500 %N A164634 Number of reduced words of length n in Coxeter group on 21 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I. %C A164634 The initial terms coincide with those of A170740, although the two sequences are eventually different. %C A164634 Computed with MAGMA using commands similar to those used to compute A154638. %H A164634 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (19,19,19,19,19,19,-190). %F A164634 G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(190*t^7 - 19*t^6 - 19*t^5 - 19*t^4 - 19*t^3 - 19*t^2 - 19*t + 1). %K A164634 nonn %O A164634 0,2 %A A164634 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009