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 A134291 Tenth column (and diagonal) of Narayana triangle A001263. 7
 1, 55, 1210, 15730, 143143, 1002001, 5725720, 27810640, 118195220, 449141836, 1551580888, 4936848280, 14620666060, 40648664980, 106847919376, 267119798440, 638337753625, 1464421905375, 3237143159250, 6917263803450 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS See a comment under A134288 on the coincidence of column and diagonal sequences. Kekul\'e numbers K(O(1,9,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. LINKS FORMULA a(n)= A001263(n+10,10) = binomial(n+10,10)*binomial(n+10,9)/(n+10). O.g.f.: P(9,x)/(1-x)^19 with the numerator polynomial P(9,x)=sum(A001263(9,k)*x^(k-1),k=1..9), the ninth row polynomial of the Narayana triangle. P(9,x)=1+36*x+336*x^2+1176*x^3+1764*x^4+1176*x^5+336*x^6+36*x^7+x^8. CROSSREFS Cf. A134290 (ninth column of Narayana triangle). Sequence in context: A221786 A008402 A203872 * A157096 A017771 A222836 Adjacent sequences:  A134288 A134289 A134290 * A134292 A134293 A134294 KEYWORD nonn,easy AUTHOR Wolfdieter Lang Nov 13 2007 STATUS approved

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