A089598 G.f.: (1+x^2+x^3)/(1-x^3)^2.

1, 0, 1, 3, 0, 2, 5, 0, 3, 7, 0, 4, 9, 0, 5, 11, 0, 6, 13, 0, 7, 15, 0, 8, 17, 0, 9, 19, 0, 10, 21, 0, 11, 23, 0, 12, 25, 0, 13, 27, 0, 14, 29, 0, 15, 31, 0, 16, 33, 0, 17, 35, 0, 18, 37, 0, 19, 39, 0, 20, 41, 0, 21, 43, 0, 22, 45, 0, 23, 47, 0, 24, 49, 0, 25, 51, 0, 26, 53, 0, 27, 55, 0, 28, 57

Offset

0,4

Comments

Poincaré series [or Poincare series] (or Molien series) for F_4[x_1, y_1]^{Z/3}.

References

A. Adem and R. J. Milgram, Cohomology of Finite Groups, Springer-Verlag, 2nd. ed., 2004; p. 91.

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).

Formula

a(0)=1, a(1)=0, a(2)=1, a(3)=3, a(4)=0, a(5)=2, a(n)=2*a(n-3)-a(n-6). - Harvey P. Dale, May 20 2012

Mathematica

CoefficientList[Series[(1+x^2+x^3)/(1-x^3)^2, {x, 0, 90}], x] (* or *) LinearRecurrence[{0, 0, 2, 0, 0, -1}, {1, 0, 1, 3, 0, 2}, 90] (* Harvey P. Dale, May 20 2012 *)

Crossrefs

Cf. A005408 (trisection), A000027 (trisection).

Sequence in context: A292244 A208329 A283025 * A117139 A159959 A260211

Adjacent sequences: A089595 A089596 A089597 * A089599 A089600 A089601

Keyword

nonn,easy

Author

N. J. A. Sloane, Dec 31 2003

Status

approved