OFFSET
0,2
REFERENCES
Per Hakan Lundow, Computation of matching polynomials and the number of 1-factors in polygraphs, Research reports, No 12, 1996, Department of Mathematics, Umea University.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..450
Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
FORMULA
G.f.: -(x^16 +5*x^15 -144*x^14 -917*x^13 +2525*x^12 +18314*x^11 -9907*x^10 -81619*x^9 +18056*x^8 +116675*x^7 -14719*x^6 -49054*x^5 -187*x^4 +4457*x^3 -20*x^2 -69*x +1) / (x^18 +6*x^17 -210*x^16 -1164*x^15 +10306*x^14 +54922*x^13 -76144*x^12 -470662*x^11 +132726*x^10 +1274736*x^9 +24246*x^8 -1032670*x^7 -58000*x^6 +244690*x^5 +158*x^4 -15844*x^3 +722*x^2 +98*x -1). - Alois P. Heinz, Dec 09 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved