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A164892
Number of reduced words of length n in Coxeter group on 18 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.
0
1, 18, 306, 5202, 88434, 1503378, 25557426, 434476242, 7386095961, 125563628736, 2134581644448, 36287887206528, 616894069776480, 10487198969713728, 178282378804864032, 3030800377118109696, 51523605347410047672
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170737, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
FORMULA
G.f. (t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(136*t^8 -
16*t^7 - 16*t^6 - 16*t^5 - 16*t^4 - 16*t^3 - 16*t^2 - 16*t + 1)
MATHEMATICA
coxG[{8, 136, -16}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Mar 06 2024 *)
CROSSREFS
Sequence in context: A163452 A163967 A164630 * A165329 A165880 A166412
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved