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URL: https://oeis.org/A107965

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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
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
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) / (x-1)^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
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jun 12 2005
STATUS
approved