OFFSET
0,2
COMMENTS
Kekulé numbers for certain benzenoids.
REFERENCES
S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 168).
LINKS
Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).
FORMULA
G.f.: -(2*x^3+10*x^2+8*x+1)/(x-1)^7. - Alois P. Heinz, Feb 27 2015
MAPLE
a:=n->(n+1)*(n+2)^2*(n+3)*(7*n^2+23*n+20)/240: seq(a(n), n=0..33);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Nov 18 2005
STATUS
approved