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A120286
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Numerator of 1/n^2 + 2/(n-1)^2 + 3/(n-2)^2 +...+ (n-1)/2^2 + n.
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0
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1, 9, 65, 725, 3899, 28763, 419017, 864669, 7981633, 3586319, 200763407, 2649665993, 34899471137, 176508049513, 356606957297, 12234391348253, 209672027529221, 4012917216669239, 15350275129353301, 15443118015171841
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| p^2 divides a(p-1) for prime p>2. p divides a(p-2) for prime p>3.
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FORMULA
| a(n) = numerator[Sum[Sum[1/i^2,{i,1,k}],{k,1,n}]].
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MATHEMATICA
| Numerator[Table[Sum[Sum[1/i^2, {i, 1, k}], {k, 1, n}], {n, 1, 30}]]
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CROSSREFS
| Cf. A027612, A001008, A007406, A007407.
Sequence in context: A128195 A103459 A100311 * A152581 A122733 A118465
Adjacent sequences: A120283 A120284 A120285 * A120287 A120288 A120289
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KEYWORD
| frac,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Jul 07 2006
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