OFFSET
1,4
LINKS
S. J. Cyvin, B. N. Cyvin, J. Brunvoll, Zhang Fuji, Guo Xiaofeng, R. Tosic, Graph-theoretical studies on fluoranthenoids and fluorenoids: enumeration of some catacondensed systems, J. Molec. Struct. (Theochem), 285 (1993), 179-185.
FORMULA
G.f.: (6*x^3 - 12*x^2 + 6*x + (2*x^2-3*x+1) * sqrt(1-x) * sqrt(1-5*x) - sqrt(1-x^2) * sqrt(1-5*x^2)) / (4*x*(x-1)). - Sean A. Irvine, Jun 26 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, May 03 2000
EXTENSIONS
More terms from Sean A. Irvine, Jun 26 2019
STATUS
approved