A164674 Number of reduced words of length n in Coxeter group on 38 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 38, 1406, 52022, 1924814, 71218118, 2635070366, 97497602839, 3607411279032, 133474216362480, 4938545969828712, 182726199567089568, 6760869335269121304, 250152163602569357904, 9255629986606705913226

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170757, 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 (36, 36, 36, 36, 36, 36, -666).

Formula

G.f. (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(666*t^7 - 36*t^6 -

36*t^5 - 36*t^4 - 36*t^3 - 36*t^2 - 36*t + 1)