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A030520 Number of polyhexes of class PF2 with C_{2n} symmetry. 9
0, 1, 5, 20, 82, 335, 1402, 5949, 25652, 111963, 494157, 2201270, 9886034, 44712737, 203489627, 931191850, 4282171470, 19778577235, 91715812335, 426824400684, 1992828161414, 9332192498397, 43821128181652, 206288470970025, 973361629499032, 4602638827207605 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

COMMENTS

See reference for precise definition.

LINKS

Table of n, a(n) for n=2..27.

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.

CROSSREFS

Cf. A026106, A026118, A026298, A030519, A030520, A030525, A030529, A030532, A030534.

Sequence in context: A022021 A165203 A249946 * A183933 A323262 A295601

Adjacent sequences:  A030517 A030518 A030519 * A030521 A030522 A030523

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Title improved, a(2)=0 inserted, and more terms from Sean A. Irvine, Apr 02 2020

STATUS

approved

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Last modified September 24 14:46 EDT 2021. Contains 347643 sequences. (Running on oeis4.)