A162833 Number of reduced words of length n in Coxeter group on 30 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 30, 870, 24795, 706440, 20121360, 573111630, 16323709080, 464941707720, 13242748348620, 377187895691040, 10743291699776160, 305996872843541880, 8715586321562342880, 248242553013255652320, 7070593171000425862320

Offset

0,2

Comments

The initial terms coincide with those of A170749, 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 (28, 28, -406).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(406*t^3 - 28*t^2 - 28*t + 1)

Mathematica

coxG[{3, 406, -28}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Oct 20 2023 *)

Crossrefs

Sequence in context: A001201 A367333 A007850 * A163208 A163552 A164027

Adjacent sequences: A162830 A162831 A162832 * A162834 A162835 A162836

Keyword

nonn

Author

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

Status

approved