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 A165796 Number of reduced words of length n in Coxeter group on 11 generators S_i with relations (S_i)^2 = (S_i S_j)^10 = I. 1
 1, 11, 110, 1100, 11000, 110000, 1100000, 11000000, 110000000, 1100000000, 10999999945, 109999998900, 1099999983555, 10999999781100, 109999997266500, 1099999967220000, 10999999617750000, 109999995633000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The initial terms coincide with those of A003953, although the two sequences are eventually different. Computed with MAGMA using commands similar to those used to compute A154638. a(0) = a(1) = 1 (mod 5), a(n) = 0 (mod 5) for n>=2. - G. C. Greubel, Apr 08 2016 LINKS G. C. Greubel, Table of n, a(n) for n = 0..500 Index entries for linear recurrences with constant coefficients, signature (9, 9, 9, 9, 9, 9, 9, 9, 9, -45). FORMULA G.f.: (t^10 + 2*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)/(45*t^10 - 9*t^9 - 9*t^8 - 9*t^7 - 9*t^6 - 9*t^5 - 9*t^4 - 9*t^3 - 9*t^2 - 9*t + 1). MATHEMATICA CoefficientList[Series[(t^10 + 2*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)/(45*t^10 - 9*t^9 - 9*t^8 - 9*t^7 - 9*t^6 - 9*t^5 - 9*t^4 - 9*t^3 - 9*t^2 - 9*t + 1), {t, 0, 25}], t] (* G. C. Greubel, Apr 08 2016 *) CROSSREFS Sequence in context: A115830 A164780 A165264 * A166369 A166551 A166950 Adjacent sequences:  A165793 A165794 A165795 * A165797 A165798 A165799 KEYWORD nonn AUTHOR John Cannon and N. J. A. Sloane, Dec 03 2009 STATUS approved

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Last modified July 17 16:58 EDT 2019. Contains 325107 sequences. (Running on oeis4.)