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

0,2

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

Table of n, a(n) for n=0..15.

Index entries for linear recurrences with constant coefficients, signature (24,24,24,-300).

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).

Mathematica

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

Prog

(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

Crossrefs

Sequence in context: A285397 A106793 A162812 * A163526 A163995 A164639

Adjacent sequences: A163174 A163175 A163176 * A163178 A163179 A163180

Keyword

nonn

Author

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

Status

approved