A164693 - OEIS

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A164693

Number of reduced words of length n in Coxeter group on 48 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 48, 2256, 106032, 4983504, 234224688, 11008560336, 517402334664, 24317909676192, 1142941752290400, 53718262240589472, 2524758319805916768, 118663640772294032544, 5577191104144368918624, 262127981323573161732216

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OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170767, 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 (46, 46, 46, 46, 46, 46, -1081).

FORMULA

G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(1081*t^7 - 46*t^6 - 46*t^5 - 46*t^4 - 46*t^3 - 46*t^2 - 46*t + 1).

CROSSREFS

Sequence in context: A163266 A163829 A164348 * A165180 A165708 A166313

Adjacent sequences: A164690 A164691 A164692 * A164694 A164695 A164696

KEYWORD

nonn

AUTHOR

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

STATUS

approved