|
Search: id:A134289
|
|
|
| A134289 |
|
Eighth column (and diagonal) of Narayana triangle A001263. |
|
+0
3
|
|
| 1, 36, 540, 4950, 32670, 169884, 736164, 2760615, 9202050, 27810640, 77364144, 200443464, 488259720, 1126753200, 2478857040, 5226256926, 10606227291, 20796524100, 39525557500, 73018266750, 131432880150, 231003243900
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
See a comment under A134288 on the coincidence of column and diagonal sequences.
Kekul\'e numbers K(O(1,7,n)) for certain benzenoids (see the Cyvin-Gutman reference, p. 105, eq. (i)).
|
|
REFERENCES
|
S. J. Cyvin and I. Gutman, Kekul\'e structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988.
|
|
FORMULA
|
a(n)= A001263(n+8,8) = binomial(n+8,8)*binomial(n+8,7)/(n+8).
O.g.f.: P(7,x)/(1-x)^15 with the numerator polynomial P(7,x)=sum(A001263(7,k)*x^(k-1),k=1..7), the seventh row polynomial of the Narayana triangle. P(7,x)= 1+21*x+105*x^2+175*x^3+105*x^4+21*x^5+x^6.
|
|
CROSSREFS
|
Cf. A134288 (seventh column of Narayana triangle).
Cf. A134290 (ninth column of Narayana triangle).
Sequence in context: A128986 A090408 A008657 this_sequence A081447 A099764 A003841
Adjacent sequences: A134286 A134287 A134288 this_sequence A134290 A134291 A134292
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de) Nov 13 2007
|
|
|
Search completed in 0.002 seconds
|
