

A107965


a(n) = (n+1)(n+2)^2*(n+3)^2*(n+4)(11n^4 + 110n^3 + 439n^2 + 820n + 600)/86400.


2



1, 33, 421, 3171, 16954, 71148, 249228, 758934, 2066559, 5135845, 11828817, 25546885, 52216164, 101751664, 190171248, 342572508, 597234429, 1011161361, 1667449861, 2684929863, 4230610846, 6535551660, 9914869900, 14792713650, 21733135515, 31477936581
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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. 229).


LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (11,55,165,330,462,462,330,165,55,11,1).


FORMULA

G.f.: (x^6+22*x^5+113*x^4+190*x^3+113*x^2+22*x+1) / (x1)^11.  Colin Barker, Aug 13 2013


MAPLE

a:=n>(1/86400)*(n+1)*(n+2)^2*(n+3)^2*(n+4)*(11*n^4+110*n^3+439*n^2+820*n+600): seq(a(n), n=0..26);


CROSSREFS

Sequence in context: A202256 A324950 A252925 * A220591 A296839 A296988
Adjacent sequences: A107962 A107963 A107964 * A107966 A107967 A107968


KEYWORD

nonn,easy


AUTHOR

Emeric Deutsch, Jun 12 2005


STATUS

approved



