login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified November 22 18:51 EST 2014. Contains 249807 sequences.