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A164027 Number of reduced words of length n in Coxeter group on 30 generators S_i with relations (S_i)^2 = (S_i S_j)^6 = I. 1
1, 30, 870, 25230, 731670, 21218430, 615334035, 17844674400, 517495192200, 15007349977200, 435212842037400, 12621163507344000, 366013483272687390, 10614383520144862920, 307816904736225416280, 8926683934263695000520 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170749, 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..680

Index entries for linear recurrences with constant coefficients, signature (28, 28, 28, 28, 28, -406).

FORMULA

G.f.: (t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(406*t^6 - 28*t^5 - 28*t^4 - 28*t^3 - 28*t^2 - 28*t + 1).

MATHEMATICA

CoefficientList[Series[(t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(406*t^6 - 28*t^5 - 28*t^4 - 28*t^3 - 28*t^2 - 28*t + 1), {t, 0, 50}], t] (* G. C. Greubel, Sep 07 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)/(406*t^6 - 28*t^5 - 28*t^4 - 28*t^3 - 28*t^2 - 28*t + 1)) \\ G. C. Greubel, Sep 07 2017

CROSSREFS

Sequence in context: A162833 A163208 A163552 * A164666 A164983 A165515

Adjacent sequences:  A164024 A164025 A164026 * A164028 A164029 A164030

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified November 14 23:06 EST 2018. Contains 317221 sequences. (Running on oeis4.)