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%I #21 Jul 30 2019 19:29:32
%S 1,5,31,216,1617,12705,103358,863161,7357277,63747221,559809997,
%T 4971528380,44572279612,402883616972,3667455453895,33592221383213,
%U 309375866119789,2863158467711801,26613026976466819,248338952866938164,2325603300814424911,21848776123428594487
%N Number of edge-rooted 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(1) (1997), 55-70.
%H J. Brunvoll, S. 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; see Section 3 (p. 194).
%F G.f. G(x) = G satisfies G = x * (1 + 5*G + 6*G^2 + G^3).
%F a(r) = A121112(r) + A121113(r) + A121114(r) for r >= 2. - _Petros Hadjicostas_, Jul 30 2019
%p Order := 30: S := solve(series(G/(1+5*G+6*G^2+G^3),G)=x,G);
%Y Cf. A036759, A036760, A121112, A121113, A121114.
%K nonn,easy
%O 1,2
%A _N. J. A. Sloane_
%E More terms from _Emeric Deutsch_, Feb 28 2004
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