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A297151
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a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} binomial(n,i)*binomial(n,j)*binomial(n,k)*max(i,j,k).
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0
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0, 7, 100, 1128, 11552, 112160, 1052544, 9646336, 86877184, 772010496, 6787635200, 59163619328, 512002867200, 4404129513472, 37687664508928, 321065313239040, 2724508666953728, 23040146455789568, 194245982204461056, 1633162428477865984, 13697353473127874560
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OFFSET
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0,2
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COMMENTS
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The given closed-form formula is provable.
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LINKS
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FORMULA
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a(n) = n*2^(3*n-1) + 3*n*2^(n-2)*binomial(2*n, n).
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MATHEMATICA
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Table[n*2^(3n-1)+3n*2^(n-2) Binomial[2n, n], {n, 0, 20}] (* Harvey P. Dale, Nov 24 2018 *)
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CROSSREFS
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Analogous nested sum with only two levels: A100511, and with only one level: A001787.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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