A164691 Number of reduced words of length n in Coxeter group on 46 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 46, 2070, 93150, 4191750, 188628750, 8488293750, 381973217715, 17188794750600, 773495761682160, 34807309181429400, 1566328908922272000, 70484800710609945000, 3171816023387294250000, 142731720665871344945190

Offset

0,2

Comments

The initial terms coincide with those of A170765, 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 (44, 44, 44, 44, 44, 44, -990).

Formula

G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(990*t^7 - 44*t^6 - 44*t^5 - 44*t^4 - 44*t^3 - 44*t^2 - 44*t + 1).

Crossrefs

Sequence in context: A163232 A163802 A164331 * A165178 A165702 A166303

Adjacent sequences: A164688 A164689 A164690 * A164692 A164693 A164694

Keyword

nonn

Author

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

Status

approved