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%I #13 Jun 26 2022 23:55:46
%S 0,0,0,1,2,12,56,282,1365,6666,32002,153350,731156,3480594,16546884,
%T 78644579,373813930,1777680136,8459543997,40290717546,192072529566,
%U 916541991433,4378019950311,20933668637794,100196639221232
%N Catafusenes (see reference for precise definition).
%H S. J. Cyvin et al., <a href="http://dx.doi.org/10.1021/ci00021a026">Enumeration and Classification of Certain Polygonal Systems Representing Polycyclic Conjugated Hydrocarbons: Annelated Catafusenes</a>, J. Chem. Inform. Comput. Sci., 34 (1994), 1174-1180.
%H F. Harary and R. C. Read, <a href="https://doi.org/10.1017/S0013091500009135">The enumeration of tree-like polyhexes</a>, Proc. Edinburgh Math. Soc. (2) 17 (1970), 1-13.
%F G.f.: (1/2)*U(z^2)*V(z) + (1/6)*U(z)^3 + (1/3)*U(z^3) where U(z) = (1 - 3z - sqrt(1 - 6z + 5z^2))/(2z) and V(z) = (1 - z^2 - sqrt(1 - 6z^2 + 5z^4))/(2*z*(1-z)) (eq. (26) in the Cyvin et al. paper).
%K nonn
%O 0,5
%A _N. J. A. Sloane_
%E More terms from _Emeric Deutsch_, Mar 14 2004