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Search: id:A130862
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| A130862 |
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Ratio of triple Sum of k^2-1 to triple sum of k made into an integer sequence: (1/2)(-1 + n))((2 + n)(11 + 2 n). |
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+0
1
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| 0, 30, 85, 171, 294, 460, 675, 945, 1276, 1674, 2145, 2695, 3330, 4056, 4879, 5805, 6840, 7990, 9261, 10659, 12190, 13860, 15675, 17641, 19764, 22050, 24505, 27135, 29946, 32944
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Double sum ratio is:A055998
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FORMULA
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a(n) = (5/2)*(n + 2)*(n + 3)*Sum[Sum[Sum[k^2 - 1, { k, 1, m}], {m, 1, j}], {j, 1, n}]/Sum[Sum[Sum[k, {k, 1, m}], {m, 1, j}], {j, 1, n}]=(1/2)(-1 + n))((2 + n)(11 + 2 n)
G.f.: x^2*(30-35*x+11*x^2)/(-1+x)^4. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 14 2007
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MATHEMATICA
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g[n_] = (5/2)*(n + 2)*(n + 3)*Sum[Sum[Sum[k^2 - 1, {k, 1, m}], {m, 1, j}], {j, 1, n}]/Sum[Sum[Sum[k, {k, 1, m}], {m, 1, j}], {j, 1, n}]; Table[g[n], {n, 1, 30}]
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CROSSREFS
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Cf. A055998.
Sequence in context: A155461 A165772 A098996 this_sequence A070756 A058903 A103906
Adjacent sequences: A130859 A130860 A130861 this_sequence A130863 A130864 A130865
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KEYWORD
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nonn
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AUTHOR
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Roger L Bagula (rlbagulatftn(AT)yahoo.com), Jul 22 2007
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