A163093 - OEIS

A163093

Number of reduced words of length n in Coxeter group on 17 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

1, 17, 272, 4352, 69496, 1109760, 17721480, 282988800, 4518961080, 72161899200, 1152331158600, 18401221627200, 293843444945400, 4692295538064000, 74929823330517000, 1196531288107632000, 19107039891249747000, 305114439575750760000, 4872278582526960045000

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170736, 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..18.

Index entries for linear recurrences with constant coefficients, signature (15,15,15,-120).

FORMULA

G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(120*t^4 - 15*t^3 - 15*t^2 - 15*t + 1).

MATHEMATICA

CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(120 t^4 - 15 t^3 - 15 t^2 - 15 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 23 2020 *)

CROSSREFS

Sequence in context: A159678 A162803 A097830 * A163451 A163965 A164628

Adjacent sequences: A163090 A163091 A163092 * A163094 A163095 A163096

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

More terms from Jinyuan Wang, Mar 23 2020

STATUS

approved

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.