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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A121211 Number of free hexagonal polygons of symmetry class D_(2h) and area n. 1
0, 1, 1, 2, 2, 3, 3, 6, 7, 11, 14, 21, 23, 41, 50, 80, 94, 156, 189, 310, 365, 615, 748, 1237, 1459, 2488, 3023, 5059, 5994, 10296, 12511, 21149, 25100, 43451, 52870 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

REFERENCES

Markus Voege, Anthony J. Guttmann and Iwan Jensen, "On the number of benzenoid hydrocarbons", J. Chem. Inf. Comput. Sci., (2002), vol. 42, 456-466. See Table 3 under the D_(2h) column.

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

If n=10 then the number of free hexagonal polygons of symmetry class D_(2h) is 11 which is the tenth term in the sequence.

CROSSREFS

Sequence in context: A116450 A054172 A236971 * A146157 A238363 A255254

Adjacent sequences:  A121208 A121209 A121210 * A121212 A121213 A121214

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Aug 19 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 13 00:17 EST 2017. Contains 295954 sequences.