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%I #36 Mar 27 2021 23:48:33
%S 0,0,1,4,17,66,269,1102,4635,19768,85659,375524,1664015,7438862,
%T 33515027,152016610,693622315,3181516040,14661568795,67850245684,
%U 315187594779,1469195413102,6869889480447,32215398047474,151467333043437,713881813137776,3372142135461789
%N Number of polyhexes of class PF2 with a particular symmetry.
%C See references for precise definition.
%C Column D_{2h}(b) and Eq. 50 in Cyvin et al. (1994). - _Sean A. Irvine_, Mar 27 2021
%H S. J. Cyvin, J. Brunvoll, and B. N. Cyvin, <a href="https://doi.org/10.1007/BF01172927">Harary-Read numbers for catafusenes: Complete classification according to symmetry</a>, Journal of mathematical chemistry 9.1 (1992): 19-31 and 33-38. See pages 30 and 38.
%H S. J. Cyvin, B. N. Cyvin, J. Brunvoll and E. Brendsdal, <a href="https://doi.org/10.1021/ci00021a026">Enumeration and Classification of Certain Polygonal Systems Representing Polycyclic Conjugated Hydrocarbons: Annelated Catafusenes</a>, Journal of Chemical Information and Modeling [formerly, J. Chem. Inform. Comput. Sci.], 34 (1994), pp. 1174-1180.
%H S. J. Cyvin, Zhang Fuji, B. N. Cyvin, Guo Xiaofeng, and J. Brunvoll, <a href="https://doi.org/10.1021/ci00009a021">Enumeration and classification of benzenoid systems. 32. Normal perifusenes with two internal vertices</a>, J. Chem. Inform. Comput. Sci., 32 (1992), 532-540.
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a030/A030529.java">Java program</a> (github)
%F a(2)=0, a(n+2) = (M(2*n+1) - M(2*n) - M(n)) / 2 where M(n) = A055879(n) [Cyvin Eq. (54)]. - _Sean A. Irvine_, Apr 03 2020
%o (PARI) A055879(n)= my(A); if( n<1, 0, n--; A = O(x); for( k = 0, n\2, A = 1 / (1 - x - x^2 / (1 + x - x^2 * A))); polcoeff( A, n));
%o b(n) = (A055879(2*n+1) - A055879(2*n) - A055879(n)) / 2;
%o a(n) = if( n<=2, 0, b(n - 2)); \\ _Michel Marcus_, Apr 03 2020
%Y Cf. A026106, A026118, A026298, A030519, A030520, A030525, A030529, A030532, A030534.
%K nonn
%O 2,4
%A _N. J. A. Sloane_.
%E More terms from _Sean A. Irvine_, Apr 03 2020
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