A163174 Number of reduced words of length n in Coxeter group on 24 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

1, 24, 552, 12696, 291732, 6703488, 154034496, 3539441664, 81330144060, 1868823662376, 42942280730712, 986738081076264, 22673505553878564, 520997277758500752, 11971601073631152624, 275086336118245407888

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170743, 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 (22,22,22,-253).

Programs

Mathematica

CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(253 t^4 - 22 t^3 - 22 t^2 - 22 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 23 2020 *)

Formula

G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(253*t^4 - 22*t^3 - 22*t^2 - 22*t + 1).