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A165365

Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.

1, 23, 506, 11132, 244904, 5387888, 118533536, 2607737792, 57370231424, 1262145091075, 27767191998084, 610878223835649, 13439320921695900, 295665060218165484, 6504631323498465696, 143101889088340396368

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OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170742, 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 (21, 21, 21, 21, 21, 21, 21, 21, -231).

FORMULA

G.f. (t^9 + 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +

1)/(231*t^9 - 21*t^8 - 21*t^7 - 21*t^6 - 21*t^5 - 21*t^4 - 21*t^3 -

21*t^2 - 21*t + 1)

MATHEMATICA

coxG[{9, 231, -21}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Dec 25 2024 *)

CROSSREFS

Sequence in context: A163991 A164636 A164957 * A165939 A166417 A166610

Adjacent sequences: A165362 A165363 A165364 * A165366 A165367 A165368

KEYWORD

nonn

AUTHOR

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

STATUS

approved

URL: https://oeis.org/A165365

⇱ A165365 - OEIS