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A164626 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I. 0
1, 15, 210, 2940, 41160, 576240, 8067360, 112942935, 1581199620, 22136774205, 309914552220, 4338799717980, 60743139868320, 850403171588880, 11905633390308840, 166678713297370365, 2333499827827833210 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170734, 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..16.

Index entries for linear recurrences with constant coefficients, signature (13, 13, 13, 13, 13, 13, -91).

FORMULA

G.f. (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(91*t^7 - 13*t^6 -

13*t^5 - 13*t^4 - 13*t^3 - 13*t^2 - 13*t + 1)

CROSSREFS

Sequence in context: A163091 A163440 A163962 * A164860 A165282 A165875

Adjacent sequences:  A164623 A164624 A164625 * A164627 A164628 A164629

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified October 16 20:35 EDT 2019. Contains 328103 sequences. (Running on oeis4.)