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A107917
a(n) = (n+1)(n+2)^2*(n+3)^3*(n+4)^2*(n+5)(n^2 + 6n + 10)/86400.
2
1, 34, 455, 3626, 20580, 91728, 340956, 1099890, 3166449, 8302294, 20131111, 45677996, 97894160, 199645824, 389817072, 732389580, 1329624009, 2340785370, 4008235231, 6693165094, 10923775940, 17459327600, 27374197500, 42166911150, 63900046665, 95377983246
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).
FORMULA
G.f.: (x^6+22*x^5+113*x^4+190*x^3+113*x^2+22*x+1)/(x-1)^12. - Colin Barker, Jun 06 2012
MAPLE
a:=n->(1/86400)*(n+1)*(n+2)^2*(n+3)^3*(n+4)^2*(n+5)*(n^2+6*n+10): seq(a(n), n=0..27);
CROSSREFS
Sequence in context: A159655 A271036 A244495 * A277226 A241633 A302383
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jun 12 2005
STATUS
approved