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Search: id:A124879
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| 2, 3, 6, 9, 18, 25, 29, 30, 39, 84, 91, 125, 130, 184, 195, 199, 203, 241, 245, 273, 281, 378, 552, 571, 653, 776, 901, 1099, 1215, 1224, 1235, 1315, 1412, 1657, 1942, 2076, 2085, 2743, 2745, 2855, 2859, 3517, 3717, 4183, 4188, 4362, 4547, 4728, 4783
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Eric Weisstein, Link to a section of The World of Mathematics. Harmonic Number.
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EXAMPLE
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A027612(n) begins {1, 5, 13, 77, 87, 223, 481, 4609, 4861, ...}.
Thus a(1) = 2, a(2) = 3, a(3) = 6, a(4) = 9.
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MATHEMATICA
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s=1; Do[s=s+1/(n+1); f=Numerator[(n+1)*(s-1)]; If[PrimeQ[f], Print[{n, f}]], {n, 1, 1942}]
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CROSSREFS
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A027612(n) are the numerators of second order harmonic numbers H(n, (2)) = Sum[HarmonicNumber[k], {k, 1, n}]. Corresponding primes in A027612(n) are listed in A124878(n) = A027612[ a(n) ] = {5, 13, 223, 4861, 197698279, 25472027467, 6975593267347, 218572480850557, 1592457339642613, ...}.
Cf. A001008, A002805, A067657, A056903, A027612, A124878, A124837, A124880, A124881.
Adjacent sequences: A124876 A124877 A124878 this_sequence A124880 A124881 A124882
Sequence in context: A018251 A018402 A018441 this_sequence A062865 A018264 A081741
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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), Nov 11 2006
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 29 2007
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