A165169 - OEIS

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A165169

Number of reduced words of length n in Coxeter group on 37 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.

1, 37, 1332, 47952, 1726272, 62145792, 2237248512, 80540946432, 2899474070886, 104381066527920, 3757718394142650, 135277862158086480, 4870003036573352160, 175320109276401277440, 6311523932501827576320

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OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170756, 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..14.

Index entries for linear recurrences with constant coefficients, signature (35, 35, 35, 35, 35, 35, 35, -630).

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)/(630*t^8 -

35*t^7 - 35*t^6 - 35*t^5 - 35*t^4 - 35*t^3 - 35*t^2 - 35*t + 1)

CROSSREFS

Sequence in context: A163645 A164070 A164673 * A165654 A166167 A166431

Adjacent sequences: A165166 A165167 A165168 * A165170 A165171 A165172

KEYWORD

nonn

AUTHOR

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

STATUS

approved