login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A121255 Number of conjugated cycles composed of ten carbons in (n,n)-nanotubes in terms of the number of naphthalene units. 0
0, 8, 36, 128, 420, 1320, 4032, 12064, 35532, 103360, 297660, 850128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See Table 2 on page 412 of Lukovits and Janezic paper for details.

LINKS

Table of n, a(n) for n=1..12.

I. Lukovits et al. Enumeration of conjugated circuits in nanotubes, J. Chem. Inf. Comput. Sci. 44 (2004), 410-414.

Index entries for linear recurrences with constant coefficients, signature (6, -11, 6, -1).

FORMULA

Conjecture: a(n)=6a(n-1)-11a(n-2)+6a(n-3)-a(n-4). G.f.: -4*x^2*(-2+3*x)/(x^2-3*x+1)^2. [From R. J. Mathar, Mar 18 2009]

EXAMPLE

If n=5 then the number of conjugated cycles composed of ten carbons in (n,n)-nanotubes is 420 which is the fifth term in the sequence. Here n is the number of naphthalene units.

CROSSREFS

Sequence in context: A022573 A014477 A034998 * A210656 A119767 A024208

Adjacent sequences:  A121252 A121253 A121254 * A121256 A121257 A121258

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Aug 22 2006

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 27 02:39 EDT 2021. Contains 346302 sequences. (Running on oeis4.)