OFFSET
0,3
COMMENTS
The Molien series for the finite Coxeter group of type D_k (k >= 3) has G.f. = 1/Prod_i (1-x^(1+m_i)) where the m_i are [1,3,5,...,2k-3,k-1]. If k is even only even powers of x appear, and we bisect the sequence.
REFERENCES
J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See Table 3.1, page 59.
FORMULA
G.f.: 1/((1-t^8)^2*(1-t^2)*(1-t^4)*(1-t^6)*(1-t^10)*(1-t^12)*(1-t^14)), bisected.
MATHEMATICA
Take[CoefficientList[Series[1/((1-x^8)Times@@(1-x^Range[2, 14, 2])), {x, 0, 100}], x], {1, -1, 2}] (* Harvey P. Dale, Jan 02 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 10 2016
STATUS
approved