A164695 Number of reduced words of length n in Coxeter group on 50 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 50, 2450, 120050, 5882450, 288240050, 14123762450, 692064358825, 33911153522400, 1661646519657600, 81420679319162400, 3989613279580017600, 195491050353532802400, 9579061450374592377600, 469374010237877795941800

Offset

0,2

Comments

The initial terms coincide with those of A170769, 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..14.

Index entries for linear recurrences with constant coefficients, signature (48, 48, 48, 48, 48, 48, -1176).

Formula

G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(1176*t^7 - 48*t^6 - 48*t^5 - 48*t^4 - 48*t^3 - 48*t^2 - 48*t + 1).

Crossrefs

Sequence in context: A163290 A163837 A164351 * A165182 A165726 A166325

Adjacent sequences: A164692 A164693 A164694 * A164696 A164697 A164698

Keyword

nonn

Author

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

Status

approved