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A163955 Number of reduced words of length n in Coxeter group on 11 generators S_i with relations (S_i)^2 = (S_i S_j)^6 = I. 1
1, 11, 110, 1100, 11000, 110000, 1099945, 10998900, 109983555, 1099781100, 10997266500, 109967220000, 1099617752970, 10995633086625, 109950886704780, 1099454428128375, 10993999919042250, 109934555837535000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A003953, although the two sequences are eventually different.

Computed with MAGMA using commands similar to those used to compute A154638.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..995

Index entries for linear recurrences with constant coefficients, signature (9, 9, 9, 9, 9, -45).

FORMULA

G.f.: (t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(45*t^6 - 9*t^5 - 9*t^4 - 9*t^3 - 9*t^2 - 9*t + 1).

MATHEMATICA

CoefficientList[Series[(t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(45*t^6 - 9*t^5 - 9*t^4 - 9*t^3 - 9*t^2 - 9*t + 1), {t, 0, 50}], t] (* G. C. Greubel, Aug 13 2017 *)

PROG

(PARI) t='t+O('t^50); Vec((t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(45*t^6 - 9*t^5 - 9*t^4 - 9*t^3 - 9*t^2 - 9*t + 1)) \\ G. C. Greubel, Aug 13 2017

CROSSREFS

Sequence in context: A162987 A163404 A115808 * A164590 A115806 A115830

Adjacent sequences:  A163952 A163953 A163954 * A163956 A163957 A163958

KEYWORD

nonn

AUTHOR

John Cannon and N. J. A. Sloane, Dec 03 2009

STATUS

approved

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Last modified July 17 14:44 EDT 2019. Contains 325106 sequences. (Running on oeis4.)