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Search: id:A070890
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| A070890 |
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Numerator of Sum_{k=1..n} mu(k)/k when it changes sign. |
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+0
2
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| -1, 2, -1, 19, -1, 304, -81988, 410857, -249979, 4165258, -65721449, 2562470143, -5468849774, 184344882947, -137190436674212, 10026981687881, -12611493192339623
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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a(1)= -1 because numerator first sign change is 1-1/2-1/3-1/5= > (-1)/30 <0.
a(2)=2 because next sign change is -1/30+1/6 = 2/15, reverts to positive.
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PROGRAM
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PARI: t = 0; v = []; for( n = 1, 120, t1 = t; t = t + mu( n) / n; if( t * t1 < 0, v = concat( v, numer( t)), )); v
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CROSSREFS
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Cf. A070891, A070888, A070889.
Sequence in context: A089512 A089014 A063426 this_sequence A123907 A013016 A012901
Adjacent sequences: A070887 A070888 A070889 this_sequence A070891 A070892 A070893
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KEYWORD
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frac,sign,easy
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AUTHOR
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Donald S McDonald (don.mcdonald(AT)paradise.net.nz), May 17 2002.
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