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 A165939 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^10 = I. 1
 1, 23, 506, 11132, 244904, 5387888, 118533536, 2607737792, 57370231424, 1262145091328, 27767192008963, 610878224191620, 13439320932093441, 295665060503367324, 6504631331014936812, 143101889281027434912 (list; graph; refs; listen; history; text; internal format)
 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 G. C. Greubel, Table of n, a(n) for n = 0..500 Index entries for linear recurrences with constant coefficients, signature (21,21,21,21,21,21,21,21,21,-231). 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)/(231*t^10 - 21*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). MAPLE seq(coeff(series((1+t)*(1-t^10)/(1-22*t+252*t^10-231*t^11), t, n+1), t, n), n = 0..30); # G. C. Greubel, Sep 25 2019 MATHEMATICA CoefficientList[Series[(1+t)*(1-t^10)/(1-22*t+252*t^10-231*t^11), {t, 0, 25}], t] (* G. C. Greubel, Apr 18 2016 *) coxG[{10, 231, -21}] (* The coxG program is at A169452 *) (* G. C. Greubel, Sep 25 2019 *) PROG (PARI) my(t='t+O('t^30)); Vec((1+t)*(1-t^10)/(1-22*t+252*t^10-231*t^11)) \\ G. C. Greubel, Sep 25 2019 (MAGMA) R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (1+t)*(1-t^10)/(1-22*t+252*t^10-231*t^11) )); // G. C. Greubel, Sep 25 2019 (Sage) def A165939_list(prec):     P. = PowerSeriesRing(ZZ, prec)     return P((1+t)*(1-t^10)/(1-22*t+252*t^10-231*t^11)).list() A165939_list(30) # G. C. Greubel, Sep 25 2019 (GAP) a:=[23, 506, 11132, 244904, 5387888, 118533536, 2607737792, 57370231424, 1262145091328, 27767192008963];; for n in [11..30] do a[n]:=21*Sum([1..9], j-> a[n-j]) -231*a[n-10]; od; Concatenation([1], a); # G. C. Greubel, Sep 25 2019 CROSSREFS Sequence in context: A164636 A164957 A165365 * A166417 A166610 A167076 Adjacent sequences:  A165936 A165937 A165938 * A165940 A165941 A165942 KEYWORD nonn AUTHOR John Cannon and N. J. A. Sloane, Dec 03 2009 STATUS approved

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Last modified December 15 17:03 EST 2019. Contains 330000 sequences. (Running on oeis4.)