A165181 Number of reduced words of length n in Coxeter group on 49 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.

1, 49, 2352, 112896, 5419008, 260112384, 12485394432, 599298932736, 28766348770152, 1380784740910848, 66277667561012376, 3181328042798594304, 152703746048092538880, 7329779810008922456064, 351829430866051346202624

Offset

0,2

Comments

The initial terms coincide with those of A170768, 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 (47, 47, 47, 47, 47, 47, 47, -1128).

Formula

G.f. (t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(1128*t^8 -

47*t^7 - 47*t^6 - 47*t^5 - 47*t^4 - 47*t^3 - 47*t^2 - 47*t + 1)

Crossrefs

Sequence in context: A163835 A164350 A164694 * A165709 A166324 A166443

Adjacent sequences: A165178 A165179 A165180 * A165182 A165183 A165184

Keyword

nonn

Author

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

Status

approved