A164672 Number of reduced words of length n in Coxeter group on 36 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.

1, 36, 1260, 44100, 1543500, 54022500, 1890787500, 66177561870, 2316214643400, 81067511747880, 2837362884186600, 99307700001909000, 3475769467005045000, 121651930188014625000, 4257817516079844021270, 149023611645271179358500

Offset

0,2

Comments

The initial terms coincide with those of A170755, 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..15.

Index entries for linear recurrences with constant coefficients, signature (34,34,34,34,34,34,-595).

Formula

G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(595*t^7 - 34*t^6 - 34*t^5 - 34*t^4 - 34*t^3 - 34*t^2 - 34*t + 1).

Crossrefs

Sequence in context: A163219 A163601 A164069 * A165168 A165651 A166165

Adjacent sequences: A164669 A164670 A164671 * A164673 A164674 A164675

Keyword

nonn

Author

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

Status

approved