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
Alois P. Heinz, Table of n, a(n) for n = 0..600
Alois P. Heinz, G.f. for A028449
Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
FORMULA
G.f.: see link above.
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved