A164688 Number of reduced words of length n in Coxeter group on 44 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 44, 1892, 81356, 3498308, 150427244, 6468371492, 278139973210, 11960018807352, 514280806967928, 22114074624447960, 950905205618825688, 40888923702614731128, 1758223713235658179896, 75603619412131966509354

Offset

0,2

Comments

The initial terms coincide with those of A170763, 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 (42, 42, 42, 42, 42, 42, -903).

Formula

G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(903*t^7 - 42*t^6 - 42*t^5 - 42*t^4 - 42*t^3 - 42*t^2 - 42*t + 1).

Crossrefs

Sequence in context: A163230 A163748 A164277 * A165176 A165695 A166254

Adjacent sequences: A164685 A164686 A164687 * A164689 A164690 A164691

Keyword

nonn

Author

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

Status

approved