A165694 - OEIS

A165694

Number of reduced words of length n in Coxeter group on 43 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.

1, 43, 1806, 75852, 3185784, 133802928, 5619722976, 236028364992, 9913191329664, 416354035844985, 17486869505451444, 734448519227368659, 30846837807482620140, 1295567187911461777284, 54413821892163447364896

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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.

LINKS

Table of n, a(n) for n=0..14.

Index entries for linear recurrences with constant coefficients, signature (41, 41, 41, 41, 41, 41, 41, 41, -861).

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)/(861*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)

CROSSREFS

Sequence in context: A164113 A164687 A165175 * A166233 A166437 A166717

Adjacent sequences: A165691 A165692 A165693 * A165695 A165696 A165697

KEYWORD

nonn

AUTHOR

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

STATUS

approved