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A119962
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Largest prime factor of the odd denominator of n * n-th harmonic number = A027611[2^n].
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0
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3, 7, 13, 31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, 32749
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| It appears that a(n) = A014234[n] for n>1.
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FORMULA
| a(n) = Max[ FactorInteger[ Denominator[ 2^n * Sum[1/k, {k,1,2^n} ]]]].
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MATHEMATICA
| Table[Max[Flatten[FactorInteger[Denominator[2^n*Sum[1/k, {k, 1, 2^n}]]]]], {n, 2, 15}]
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CROSSREFS
| Cf. A119526, A027611, A014234.
Sequence in context: A068679 A006978 A060424 * A110436 A126879 A155128
Adjacent sequences: A119959 A119960 A119961 * A119963 A119964 A119965
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KEYWORD
| nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Aug 02 2006
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