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A036758 Number of edge-rooted tree-like octagonal systems. 12
1, 5, 31, 216, 1617, 12705, 103358, 863161, 7357277, 63747221, 559809997, 4971528380, 44572279612, 402883616972, 3667455453895, 33592221383213, 309375866119789, 2863158467711801, 26613026976466819, 248338952866938164, 2325603300814424911, 21848776123428594487 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

S. J. Cyvin, B. N. Cyvin, and J. Brunvoll, Enumeration of tree-like octagonal systems: catapolyoctagons, ACH Models in Chem. 134(1) (1997), 55-70.

LINKS

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

J. Brunvoll, S. J. Cyvin, and B. N. Cyvin, Enumeration of tree-like octagonal systems, J. Math. Chem. 21 (1997), 193-196; see Section 3 (p. 194).

FORMULA

G.f. G(x) = G satisfies G = x * (1 + 5*G + 6*G^2 + G^3).

a(r) = A121112(r) + A121113(r) + A121114(r) for r >= 2. - Petros Hadjicostas, Jul 30 2019

MAPLE

Order := 30: S := solve(series(G/(1+5*G+6*G^2+G^3), G)=x, G);

CROSSREFS

Cf. A036759, A036760, A121112, A121113, A121114.

Sequence in context: A087457 A146962 A269730 * A153232 A287899 A110379

Adjacent sequences:  A036755 A036756 A036757 * A036759 A036760 A036761

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Emeric Deutsch, Feb 28 2004

STATUS

approved

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Last modified July 11 08:53 EDT 2020. Contains 335626 sequences. (Running on oeis4.)