OFFSET
0,2
COMMENTS
The Merrifield-Simmons index of a graph is the number of its independent vertex subsets.
REFERENCES
R. E. Merrifield, H. E. Simmons, Topological Methods in Chemistry, Wiley, New York, 1989.
LINKS
T. Doslic, M. S. Litz, Matchings and independent sets in polyphenylene chains, MATCH, Commun. Math. Comput. Chem., 67, 2012, 313-330.
Index entries for linear recurrences with constant coefficients, signature (17,-7).
FORMULA
a(n) = ((19+3*sqrt(29))*(17+3*sqrt(29))^n - (19-3*sqrt(29))*(17-3*sqrt(29))^n)/(6*2^n*sqrt(29)).
G.f.: (1+x)/(1-17*x+7*x^2).
MAPLE
gser := series((x+1)/(7*x^2-17*x+1), x = 0, 22): seq(coeff(gser, x, n), n = 0 .. 20);
CROSSREFS
KEYWORD
nonn
AUTHOR
Emeric Deutsch, Nov 23 2013
STATUS
approved