A164964 Number of reduced words of length n in Coxeter group on 26 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.

1, 26, 650, 16250, 406250, 10156250, 253906250, 6347656250, 158691405925, 3967285140000, 99182128297200, 2479553202360000, 61988829932250000, 1549720745137500000, 38743018549218750000, 968575461750000000000

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, 24, 24, 24, 24, -300).

Formula

G.f. (t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(300*t^8 -

24*t^7 - 24*t^6 - 24*t^5 - 24*t^4 - 24*t^3 - 24*t^2 - 24*t + 1)

Mathematica

coxG[{8, 300, -24}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Jul 19 2015 *)

Crossrefs

Sequence in context: A163526 A163995 A164639 * A165369 A165973 A166420

Adjacent sequences: A164961 A164962 A164963 * A164965 A164966 A164967

Keyword

nonn

Author

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

Status

approved