OFFSET
4,2
COMMENTS
See reference for precise definition.
Cyvin has incorrect a(13)=369639 and a(14)=1710137 in Table III due to using incorrect values for A026298(13) and A026298(14) in Table II. - Sean A. Irvine, Apr 02 2020
LINKS
S. J. Cyvin, Zhang Fuji, B. N. Cyvin, Guo Xiaofeng, and J. Brunvoll, Enumeration and classification of benzenoid systems. 32. Normal perifusenes with two internal vertices, J. Chem. Inform. Comput. Sci., 32 (1992), 532-540.
FORMULA
a(4)=1, a(n) = A026106(n) + A026118(n) + A026298(n) + A030519(n) for n > 4. - Sean A. Irvine, Apr 02 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(13) and a(14) corrected and more terms from Sean A. Irvine, Apr 02 2020
STATUS
approved