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A036760 Number of tree-like octagonal systems. 5
1, 1, 3, 11, 56, 341, 2351, 17329, 133126, 1052813, 8511339, 70050568, 585226579, 4952310082, 42376979857, 366185395267, 3191787761573, 28036397185485, 247982793594183, 2207183342498485, 19756959439608022, 177765564883970415 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

S. J. Cyvin, B. N. Cyvin, and J. Brunvoll. Enumeration of tree-like octagonal systems: catapolyoctagons, ACH Models in Chem. 134 (1997), 55-70.

LINKS

Table of n, a(n) for n=1..22.

J. Brunvoll, J. Cyvin, and B. N. Cyvin, Enumeration of tree-like octagonal systems, J. Math. Chem., 21 (1997), 193-196.

FORMULA

G.f.: (2x + (2-7x)U(x) - (1+7x)U^2(x) + 2(2-x)V(x) + 4(1+x)U(x^2) + 3xU^2(x^2) + 2xU(x^4))/8, where U(x) is the g.f. of A036758 and V(x) is the g.f. of A036759. - Emeric Deutsch, May 04 2004

CROSSREFS

Cf. A036758, A036759, A121112, A121113, A121114.

Sequence in context: A174627 A302147 A007841 * A000985 A207433 A094611

Adjacent sequences:  A036757 A036758 A036759 * A036761 A036762 A036763

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Emeric Deutsch, May 04 2004

STATUS

approved

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Last modified January 24 07:18 EST 2020. Contains 331189 sequences. (Running on oeis4.)