A107917 a(n) = (n+1)(n+2)^2*(n+3)^3*(n+4)^2*(n+5)(n^2 + 6n + 10)/86400.

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).

Links

T. D. Noe, Table of n, a(n) for n = 0..1000

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

Adjacent sequences: A107914 A107915 A107916 * A107918 A107919 A107920

Keyword

nonn,easy

Author

Emeric Deutsch, Jun 12 2005

Status

approved