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A069220
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Denominator of Sum_{1<=k<=n, GCD(k,n)=1} 1/k.
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5
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1, 1, 2, 3, 12, 5, 20, 105, 280, 63, 2520, 385, 27720, 6435, 8008, 45045, 720720, 85085, 4084080, 2909907, 3695120, 1322685, 5173168, 37182145, 118982864, 128707425, 2974571600, 717084225, 80313433200, 215656441, 2329089562800
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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MATHEMATICA
| Table[s=0; Do[If[GCD[i, n]==1, s=s+1/i], {i, n}]; Denominator[s], {n, 1, 35}]
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PROG
| (PARI) for(n=1, 40, print1(denominator(sum(k=1, n, if(gcd(k, n)==1, 1/k))), ", "))
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CROSSREFS
| Cf. A017666, A002805.
Cf. A093600 (numerator of this sum).
Also denominators of row sums of A111879/A111880. For the numerators see A111881.
Sequence in context: A081369 A147967 A120487 * A062957 A124444 A038610
Adjacent sequences: A069217 A069218 A069219 * A069221 A069222 A069223
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KEYWORD
| nonn,frac
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AUTHOR
| Sharon Sela (sharonsela(AT)hotmail.com), Apr 12 2002
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EXTENSIONS
| More terms from Jason Earls (zevi_35711(AT)yahoo.com), Apr 14 2002
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