A162767 Number of reduced words of length n in Coxeter group on 12 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 12, 132, 1386, 14520, 151800, 1586970, 16589100, 173411700, 1812724650, 18948963000, 198079233000, 2070582104250, 21644420407500, 226255667302500, 2365118861366250, 24723302164275000, 258440148554775000

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A003954, although the two sequences are eventually different.

Computed with MAGMA using commands similar to those used to compute A154638.

Links

• Index entries for linear recurrences with constant coefficients, signature (10, 10, -55).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(55*t^3 - 10*t^2 - 10*t + 1)