A163177 Number of reduced words of length n in Coxeter group on 26 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

1, 26, 650, 16250, 405925, 10140000, 253297200, 6327360000, 158057355300, 3948270300000, 98627731207200, 2463719204700000, 61543667742382800, 1537359871188960000, 38403225875902867200, 959311990194611040000

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170745, 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 (24,24,24,-300).

Programs

Mathematica

coxG[{4,300,-24}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Jul 09 2024 *)

PARI

Vec((t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(300*t^4 - 24*t^3 - 24*t^2 - 24*t + 1) + O(t^20)) \\ Jinyuan Wang, Mar 23 2020

Formula

G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(300*t^4 - 24*t^3 - 24*t^2 - 24*t + 1).