A163175 Number of reduced words of length n in Coxeter group on 25 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

1, 25, 600, 14400, 345300, 8280000, 198547500, 4761000000, 114164729700, 2737573095600, 65644673871900, 1574103433035600, 37745661174674100, 905108843301991200, 21703740051934476300, 520437222249938431200

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170744, 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 (23,23,23,-276).

Programs

Mathematica

CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(276 t^4 - 23 t^3 - 23 t^2 - 23 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 23 2020 *)
coxG[{4,276,-23}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Aug 16 2023 *)

Formula

G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(276*t^4 - 23*t^3 - 23*t^2 - 23*t + 1).