|
| |
|
|
A109113
|
|
a(n)=6a(n-1)+3a(n-2), a(0)=2, a(1)=14.
|
|
0
| |
|
|
2, 14, 90, 582, 3762, 24318, 157194, 1016118, 6568290, 42458094, 274453434, 1774094886, 11467929618, 74129862366, 479182963050, 3097487365398, 20022473081538, 129427300585422, 836631222757146, 5408069238299142
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,1
|
|
|
COMMENTS
| Kekule numbers for certain benzenoids.
|
|
|
REFERENCES
| S. J. Cyvin and I. Gutman, Kekule structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (pp. 302, P_{15}).
|
|
|
FORMULA
| a(n)=[(3+2sqrt(3))^(n+1)+(3-2sqrt(3))^(n+1)]/3. G=2(1+z)/(1-6z-3z^2).
|
|
|
MAPLE
| a[0]:=2: a[1]:=14: for n from 2 to 25 do a[n]:=6*a[n-1]+3*a[n-2] od: seq(a[n], n=0..22);
|
|
|
CROSSREFS
| Sequence in context: A065892 A139183 A174705 * A081959 A002464 A020063
Adjacent sequences: A109110 A109111 A109112 * A109114 A109115 A109116
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 19 2005
|
| |
|
|
