

A164969


Number of reduced words of length n in Coxeter group on 27 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.


0



1, 27, 702, 18252, 474552, 12338352, 320797152, 8340725952, 216858874401, 5638330725300, 146596598620875, 3811511557982700, 99099300347388900, 2576581804867917600, 66991126818296818800, 1741769294460722280000
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OFFSET

0,2


COMMENTS

The initial terms coincide with those of A170746, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.


LINKS

Table of n, a(n) for n=0..15.
Index entries for linear recurrences with constant coefficients, signature (25, 25, 25, 25, 25, 25, 25, 325).


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)/(325*t^8 
25*t^7  25*t^6  25*t^5  25*t^4  25*t^3  25*t^2  25*t + 1)


CROSSREFS

Sequence in context: A163527 A164017 A164644 * A165445 A165979 A166421
Adjacent sequences: A164966 A164967 A164968 * A164970 A164971 A164972


KEYWORD

nonn


AUTHOR

John Cannon and N. J. A. Sloane, Dec 03 2009


STATUS

approved



