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 A170724 Number of reduced words of length n in Coxeter group on 43 generators S_i with relations (S_i)^2 = (S_i S_j)^50 = I. 1
 1, 43, 1806, 75852, 3185784, 133802928, 5619722976, 236028364992, 9913191329664, 416354035845888, 17486869505527296, 734448519232146432, 30846837807750150144, 1295567187925506306048, 54413821892871264854016 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The initial terms coincide with those of A170762, although the two sequences are eventually different. Computed with MAGMA using commands similar to those used to compute A154638. About the initial comment, first disagreement is at index 50 and the difference is 903.  - Vincenzo Librandi, Dec 07 2012 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA G.f. (t^50 + 2*t^49 + 2*t^48 + 2*t^47 + 2*t^46 + 2*t^45 + 2*t^44 + 2*t^43 + 2*t^42 + 2*t^41 + 2*t^40 + 2*t^39 + 2*t^38 + 2*t^37 + 2*t^36 + 2*t^35 + 2*t^34 + 2*t^33 + 2*t^32 + 2*t^31 + 2*t^30 + 2*t^29 + 2*t^28 + 2*t^27 + 2*t^26 + 2*t^25 + 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 2*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)/(861*t^50 - 41*t^49 - 41*t^48 - 41*t^47 - 41*t^46 - 41*t^45 - 41*t^44 - 41*t^43 - 41*t^42 - 41*t^41 - 41*t^40 - 41*t^39 - 41*t^38 - 41*t^37 - 41*t^36 - 41*t^35 - 41*t^34 - 41*t^33 - 41*t^32 - 41*t^31 - 41*t^30 - 41*t^29 - 41*t^28 - 41*t^27 - 41*t^26 - 41*t^25 - 41*t^24 - 41*t^23 - 41*t^22 - 41*t^21 - 41*t^20 - 41*t^19 - 41*t^18 - 41*t^17 - 41*t^16 - 41*t^15 - 41*t^14 - 41*t^13 - 41*t^12 - 41*t^11 - 41*t^10 - 41*t^9 - 41*t^8 - 41*t^7 - 41*t^6 - 41*t^5 - 41*t^4 - 41*t^3 - 41*t^2 - 41*t + 1) MATHEMATICA With[{num = Total[2 t^Range[49]] + t^50 + 1, den = Total[-41 t^Range[49]] + 861 t^50 + 1}, CoefficientList[Series[num/den, {t, 0, 20}], t]] (* Vincenzo Librandi, Dec 07 2012 *) CROSSREFS Sequence in context: A170580 A170628 A170676 * A170762 A218745 A009987 Adjacent sequences:  A170721 A170722 A170723 * A170725 A170726 A170727 KEYWORD nonn AUTHOR John Cannon (john(AT)maths.usyd.edu.au) and N. J. A. Sloane, Dec 03 2009 STATUS approved

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