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A096941
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Fourth column of (1,5)-Pascal triangle A096940.
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4
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5, 16, 34, 60, 95, 140, 196, 264, 345, 440, 550, 676, 819, 980, 1160, 1360, 1581, 1824, 2090, 2380, 2695, 3036, 3404, 3800, 4225, 4680, 5166, 5684, 6235, 6820, 7440, 8096, 8789, 9520, 10290, 11100, 11951, 12844, 13780, 14760, 15785, 16856, 17974, 19140
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OFFSET
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0,1
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COMMENTS
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If Y is a 5-subset of an n-set X then, for n>=7, a(n-7) is the number of 3-subsets of X having at most one element in common with Y. - Milan Janjic, Dec 08 2007
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LINKS
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FORMULA
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a(n)= (n+15)*(n+2)*(n+1)/6 = 5*b(n)-4*b(n-1), with b(n):=A000292(n)=binomial(n+3, 3).
G.f.: (5-4*x)/(1-x)^4.
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MATHEMATICA
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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