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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A107969 a(n) = (n+1)(n+2)^2*(n+3)(2n+3)(5n^2 + 19n + 20)/720. 0
1, 22, 182, 915, 3388, 10192, 26376, 60894, 128535, 252406, 467038, 822185, 1387386, 2257360, 3558304, 5455164, 8159949, 11941158, 17134390, 24154207, 33507320, 45807168, 61789960, 82332250, 108470115, 141420006, 182601342 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Kekulé numbers for certain benzenoids.

REFERENCES

S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 230).

LINKS

Table of n, a(n) for n=0..26.

MAPLE

a:=n->(1/720)*(n+1)*(n+2)^2*(n+3)*(2*n+3)*(5*n^2+19*n+20): seq(a(n), n=0..30);

CROSSREFS

Sequence in context: A125359 A126517 A197496 * A248489 A248490 A191012

Adjacent sequences:  A107966 A107967 A107968 * A107970 A107971 A107972

KEYWORD

nonn,easy

AUTHOR

Emeric Deutsch, Jun 12 2005

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 January 18 01:05 EST 2020. Contains 330995 sequences. (Running on oeis4.)