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A165269
Number of reduced words of length n in Coxeter group on 13 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.
0
1, 13, 156, 1872, 22464, 269568, 3234816, 38817792, 465813504, 5589761970, 67077142704, 804925701294, 9659108281680, 115909297773984, 1390911554013696, 16690938416875008, 200291258227027968
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170732, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
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)/(66*t^9 - 11*t^8 - 11*t^7 - 11*t^6 - 11*t^5 - 11*t^4 - 11*t^3 -
11*t^2 - 11*t + 1)
MATHEMATICA
coxG[{9, 66, -11}] (* The coxG program is at A169452 *) (* Harvey P. Dale, May 03 2022 *)
CROSSREFS
Sequence in context: A163958 A164610 A164815 * A165873 A166377 A166558
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved