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%I #16 Jul 30 2019 04:37:11
%S 1,1,3,11,56,341,2351,17329,133126,1052813,8511339,70050568,585226579,
%T 4952310082,42376979857,366185395267,3191787761573,28036397185485,
%U 247982793594183,2207183342498485,19756959439608022,177765564883970415
%N Number of tree-like octagonal systems.
%D S. J. Cyvin, B. N. Cyvin, and J. Brunvoll. Enumeration of tree-like octagonal systems: catapolyoctagons, ACH Models in Chem. 134 (1997), 55-70.
%H J. Brunvoll, J. Cyvin, and B. N. Cyvin, <a href="http://dx.doi.org/10.1023/A:1019122419384">Enumeration of tree-like octagonal systems</a>, J. Math. Chem., 21 (1997), 193-196.
%F 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
%Y Cf. A036758, A036759, A121112, A121113, A121114.
%K nonn,easy
%O 1,3
%A _N. J. A. Sloane_
%E More terms from _Emeric Deutsch_, May 04 2004