A165688 Number of reduced words of length n in Coxeter group on 39 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.

1, 39, 1482, 56316, 2140008, 81320304, 3090171552, 117426518976, 4462207721088, 169563893400603, 6443427949194756, 244850262068331465, 9304309958555963676, 353563778423582603916, 13435423580037466349472

Offset

0,2

Comments

The initial terms coincide with those of A170758, 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 (37, 37, 37, 37, 37, 37, 37, 37, -703).

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)/(703*t^9 - 37*t^8 - 37*t^7 - 37*t^6 - 37*t^5 - 37*t^4 - 37*t^3 -

37*t^2 - 37*t + 1)

Crossrefs

Sequence in context: A164084 A164681 A165171 * A166171 A166433 A166691

Adjacent sequences: A165685 A165686 A165687 * A165689 A165690 A165691

Keyword

nonn

Author

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

Status

approved