OFFSET
0,2
REFERENCES
Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research report, No 12, 1996, Department of Math., Umea University, Sweden.
LINKS
Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
FORMULA
G.f.: -(x^4 +2*x^3 -4*x^2 -2*x +1) / (x^6 +4*x^5 -16*x^4 -6*x^3 +16*x^2 +4*x -1).
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved