A163090 Number of reduced words of length n in Coxeter group on 14 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

1, 14, 182, 2366, 30667, 397488, 5152056, 66777984, 865538310, 11218616136, 145409328792, 1884713116104, 24428580744204, 316629386210592, 4103970233205024, 53193330778861728, 689461735481280216, 8936411345795737440, 115828687266480560736, 1501305644372339725920

Offset

0,2

Comments

The initial terms coincide with those of A170733, 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..19.

Index entries for linear recurrences with constant coefficients, signature (12,12,12,-78).

Formula

G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(78*t^4 - 12*t^3 - 12*t^2 - 12*t + 1).

Mathematica

CoefficientList[ Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(78 t^4 - 12 t^3 - 12 t^2 - 12 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 22 2020 *)

Crossrefs

Sequence in context: A097828 A030008 A342883 * A163439 A163959 A164618

Adjacent sequences: A163087 A163088 A163089 * A163091 A163092 A163093

Keyword

nonn

Author

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

Extensions

More terms from Jinyuan Wang, Mar 22 2020

Status

approved