A164687 Number of reduced words of length n in Coxeter group on 43 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 43, 1806, 75852, 3185784, 133802928, 5619722976, 236028364089, 9913191253812, 416354031068115, 17486869237997292, 734448505187617668, 30846837099932661024, 1295567153243385959664, 54413820228163207379946

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170762, although the two sequences are eventually different.

Computed with MAGMA using commands similar to those used to compute A154638.

Links

• Index entries for linear recurrences with constant coefficients, signature (41, 41, 41, 41, 41, 41, -861).

Programs

Mathematica

coxG[{7,861,-41}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Aug 30 2016 *)

Formula

G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(861*t^7 - 41*t^6 - 41*t^5 - 41*t^4 - 41*t^3 - 41*t^2 - 41*t + 1).