A036760 Number of tree-like octagonal systems.

1, 1, 3, 11, 56, 341, 2351, 17329, 133126, 1052813, 8511339, 70050568, 585226579, 4952310082, 42376979857, 366185395267, 3191787761573, 28036397185485, 247982793594183, 2207183342498485, 19756959439608022, 177765564883970415

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