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A163091 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I. 0
1, 15, 210, 2940, 41055, 573300, 8005725, 111793500, 1561106820, 21799608285, 304414090890, 4250899269435, 59360407871310, 828920611657320, 11575213262103855, 161638593827703720, 2257153663002754425, 31519345335542489880, 440142444293996873520, 6146237150764726493205 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170734, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
LINKS
FORMULA
G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(91*t^4 - 13*t^3 - 13*t^2 - 13*t + 1).
MATHEMATICA
CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(91 t^4 - 13 t^3 - 13 t^2 - 13 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 22 2020 *)
CROSSREFS
Cf. A170734.
Sequence in context: A000483 A162785 A076139 * A163440 A163962 A164626
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
EXTENSIONS
More terms from Jinyuan Wang, Mar 22 2020
STATUS
approved

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Last modified March 19 03:33 EDT 2024. Contains 370952 sequences. (Running on oeis4.)