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Search: id:A099866
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| A099866 |
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Denominator of sum of all elements M(i,j,k) = i*j/k, (i,j,k = 1..n). a(n) = Denominator[Sum[Sum[Sum[i*j/k,{i,1,n}],{j,1,n}],{k,1,n}]]. |
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+0
2
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| 1, 2, 1, 3, 4, 20, 5, 35, 56, 504, 70, 770, 3960, 1144, 1001, 45045, 80080, 1361360, 204204, 184756, 67184, 470288, 323323, 7436429, 27457584, 228813200, 106234700, 2868336900, 356948592, 10351509168, 145568097675, 45581929575, 85801279200
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OFFSET
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1,2
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FORMULA
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a(n) = Denominator[Sum[Sum[Sum[i*j/k, {i, 1, n}], {j, 1, n}], {k, 1, n}]]
a(n) = denominator of ((n^2+n)/2)^2*Sum(1/i, i=1..n). - Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 30 2004
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EXAMPLE
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Sum[M(i,j,k)] begins 1, 27/2, 66, 625/3, 2055/4, 21609/20, ... So a(2) = 2.
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MATHEMATICA
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Table[ Denominator[ Sum[ i*j/k, {i, n}, {j, n}, {k, n}]], {n, 33}]
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CROSSREFS
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Corresponding numerator is A099865
Cf. A099865.
Adjacent sequences: A099863 A099864 A099865 this_sequence A099867 A099868 A099869
Sequence in context: A086851 A001054 A141487 this_sequence A085189 A130466 A129322
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KEYWORD
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nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Oct 28 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 02 2004
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