OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
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.
Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
FORMULA
G.f.: (x^6 +4*x^5 -4*x^4 -16*x^3 +4*x^2 +4*x -1) / (-x^8 -8*x^7 +22*x^6 +60*x^5 -67*x^4 -60*x^3 +22*x^2 +8*x -1). - Alois P. Heinz, Dec 09 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved