A036758 Number of edge-rooted tree-like octagonal systems.

1, 5, 31, 216, 1617, 12705, 103358, 863161, 7357277, 63747221, 559809997, 4971528380, 44572279612, 402883616972, 3667455453895, 33592221383213, 309375866119789, 2863158467711801, 26613026976466819, 248338952866938164, 2325603300814424911, 21848776123428594487

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