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Search: id:A095663
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| 3, 22, 92, 288, 750, 1716, 3564, 6864, 12441, 21450, 35464, 56576, 87516, 131784, 193800, 279072, 394383, 547998, 749892, 1012000, 1348490, 1776060, 2314260, 2985840, 3817125, 4838418, 6084432, 7594752, 9414328, 11594000, 14191056
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OFFSET
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0,1
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COMMENT
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If Y is a 3-subset of an n-set X then, for n>=9, a(n-9) is the number of 7-subsets of X having at most one element in common with Y. - Milan R. Janjic (agnus(AT)blic.net), Nov 23 2007
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FORMULA
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G.f.: (3-2*x)/(1-x)^8.
a(n)= binomial(n+6, 6)*(n+21)/7 = 3*b(n)-2*b(n-1), with b(n):=binomial(n+7, 7); cf. A000580.
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CROSSREFS
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Seventh column: A095662. Ninth column: A095664.
Sequence in context: A106150 A135836 A004305 this_sequence A009029 A009032 A061182
Adjacent sequences: A095660 A095661 A095662 this_sequence A095664 A095665 A095666
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KEYWORD
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nonn,easy
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AUTHOR
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Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Jun 11 2004
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