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 A165213 Number of reduced words of length n in Coxeter group on 6 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I. 0
 1, 6, 30, 150, 750, 3750, 18750, 93750, 468750, 2343735, 11718600, 58592640, 292961400, 1464798000, 7323945000, 36619500000, 183096375000, 915476250000, 4577353125210, 22886625003000, 114432421904040, 572158593987000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The initial terms coincide with those of A003948, although the two sequences are eventually different. Computed with MAGMA using commands similar to those used to compute A154638. LINKS Index entries for linear recurrences with constant coefficients, signature (4, 4, 4, 4, 4, 4, 4, 4, -10). 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)/(10*t^9 - 4*t^8 - 4*t^7 - 4*t^6 - 4*t^5 - 4*t^4 - 4*t^3 - 4*t^2 - 4*t + 1) MATHEMATICA With[{num=Total[2t^Range]+t^9+1, den=Total[-4 t^Range]+10t^9+1}, CoefficientList[Series[num/den, {t, 0, 30}], t]] (* Harvey P. Dale, Jan 22 2012 *) CROSSREFS Sequence in context: A163922 A164365 A164741 * A165777 A166364 A166500 Adjacent sequences: A165210 A165211 A165212 * A165214 A165215 A165216 KEYWORD nonn AUTHOR John Cannon and N. J. A. Sloane, Dec 03 2009 STATUS approved

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Last modified January 31 11:56 EST 2023. Contains 359971 sequences. (Running on oeis4.)