A165366 - OEIS

A165366

Number of reduced words of length n in Coxeter group on 24 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.

1, 24, 552, 12696, 292008, 6716184, 154472232, 3552861336, 81715810728, 1879463646468, 43227663862416, 994236268689840, 22867434176514576, 525950985982745136, 12096872675830065552, 278228071503310838448

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OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170743, 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 (22, 22, 22, 22, 22, 22, 22, 22, -253).

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)/(253*t^9 - 22*t^8 - 22*t^7 - 22*t^6 - 22*t^5 - 22*t^4 - 22*t^3 -

22*t^2 - 22*t + 1)

CROSSREFS

Sequence in context: A163992 A164637 A164959 * A165965 A166418 A166611

Adjacent sequences: A165363 A165364 A165365 * A165367 A165368 A165369

KEYWORD

nonn

AUTHOR

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

STATUS

approved