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A160049
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Denominator of the Harary number for the path graph P_n.
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2
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1, 1, 1, 3, 6, 5, 10, 35, 140, 126, 1260, 1155, 13860, 12870, 12012, 45045, 360360, 340340, 2042040, 1939938, 369512, 117572, 2586584, 7436429, 178474296, 171609900, 1487285800, 1434168450, 40156716600, 38818159380, 1164544781400
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OFFSET
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1,4
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COMMENTS
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Yes, except for offset, because n*(harmonic(n)-harmonic(n-1)) = 1 which is an integer. - Andrew Howroyd, Oct 31 2017
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LINKS
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EXAMPLE
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0, 2, 5, 26/3, 77/6, 87/5, 223/10, 962/35, 4609/140, 4861/126, ...
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PROG
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(PARI)
harmonic(n)=sum(k=1, n, 1/k);
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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