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A164970 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I. 0
1, 28, 756, 20412, 551124, 14880348, 401769396, 10847773692, 292889889306, 7908027001056, 213516728753328, 5764951668909888, 155653694859957840, 4202649755802415008, 113471543260421145072, 3063731664082781293056 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170747, although the two sequences are eventually different.

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

LINKS

Table of n, a(n) for n=0..15.

Index entries for linear recurrences with constant coefficients, signature (26, 26, 26, 26, 26, 26, 26, -351).

FORMULA

G.f. (t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(351*t^8 -

26*t^7 - 26*t^6 - 26*t^5 - 26*t^4 - 26*t^3 - 26*t^2 - 26*t + 1)

CROSSREFS

Sequence in context: A163548 A164025 A164664 * A165456 A165980 A166422

Adjacent sequences:  A164967 A164968 A164969 * A164971 A164972 A164973

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified July 15 22:48 EDT 2019. Contains 325061 sequences. (Running on oeis4.)