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Search: id:A053310
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| A053310 |
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a(n)=(n+3)*C(n+8, 8)/3. |
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+0
2
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| 1, 12, 75, 330, 1155, 3432, 9009, 21450, 47190, 97240, 189618, 352716, 629850, 1085280, 1812030, 2941884, 4657983, 7210500, 10935925, 16280550, 23828805, 34337160, 48774375, 68368950, 94664700, 129585456, 175509972, 235358200
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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If Y is a 3-subset of an n-set X then, for n>=11, a(n-11) is the number of 11-subsets of X having at least two elements in common with Y. - Milan R. Janjic (agnus(AT)blic.net), Nov 23 2007
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REFERENCES
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A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 189, 194-196.
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FORMULA
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G.f.: (1+2*x)/(1-x)^10.
binomial(n+8,n+2)*binomial(n+3,n)/28. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 12 2006
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MAPLE
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seq(binomial(n+8, n+2)*binomial(n+3, n)/28, n=0 to infinity - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 12 2006
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CROSSREFS
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Partial sums of A053367.
Cf. A053367, A053347, A000581.
Cf. A093560 ((3, 1) Pascal, column m=9).
Sequence in context: A064116 A003368 A092867 this_sequence A006235 A009642 A051104
Adjacent sequences: A053307 A053308 A053309 this_sequence A053311 A053312 A053313
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KEYWORD
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easy,nonn
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AUTHOR
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Barry E. Williams, Mar 06 2000
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EXTENSIONS
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More terms from Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 12 2006
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