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A002215 Number of polyhexes with n hexagons, having reflectional symmetry (see Harary and Read for precise definition).
(Formerly M0772 N0295)
3

%I M0772 N0295

%S 1,1,2,3,6,10,20,36,72,137,274,543,1086,2219,4438,9285,18570,39587,

%T 79174,171369,342738,751236,1502472,3328218,6656436,14878455,29756910,

%U 67030785,134061570,304036170,608072340,1387247580,2774495160

%N Number of polyhexes with n hexagons, having reflectional symmetry (see Harary and Read for precise definition).

%D J. Brunvoll, S. J. Cyvin and B. N. Cyvin, Isomer enumeration of polygonal systems..., J. Molec. Struct. (Theochem), 364 (1996), 1-13. (See Table 10.)

%D F. Harary and R. C. Read, The enumeration of tree-like polyhexes, Proc. Edinb. Math. Soc. (2) 17 (1970), 1-13.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe, <a href="/A002215/b002215.txt">Table of n, a(n) for n=1..200</a>

%F G.f. = z+(1+2z)U(z^2) where U(z)=[1-3z-sqrt(1-6z+5z^2)]/(2z) (eq. (16) in the Harary-Read paper). a(2n)=A002212(n), n>=1; a(2n+1)=2*A002212(n), n>=1. - _Emeric Deutsch_, Mar 14 2004

%Y Cf. A002212.

%K nonn

%O 1,3

%A _N. J. A. Sloane_.

%E More terms from _Emeric Deutsch_, Mar 14 2004

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Last modified August 28 20:16 EDT 2015. Contains 261164 sequences.