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Search: id:A101992
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| A101992 |
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Numerator of Sum((-1)^i/(i phi(i))) 2<=i<=n. |
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+0
2
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| 1, 1, 11, 49, 59, 131, 559, 14533, 15289, 33031, 34417, 441877, 452173, 2224829, 9034451, 152504587, 155227307, 2932982513, 2967901397
(list; graph; listen)
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OFFSET
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2,3
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COMMENT
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I conjecture that there exists a limit for Sum( (-1)^i/(i*phi(i)) 2<=i<=Infinity which is ca. 0.558.
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LINKS
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Eric W.Weisstein, Totient Function.
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FORMULA
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a(n) = numerator( Sum( (-1)^i/(i*phi(i)) ) ) 2<=i<=n
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EXAMPLE
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a(3) = 11 because Sum( (-1)^i/(i*phi(i)) 2<=i<=3 = 11/24, so the numerator of 11/24 is 11.
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MATHEMATICA
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Generating the sum : f[n_Integer]/; n >= 2 := Sum[(-1)^i/(i*EulerPhi[i]), {i, 2, n}] Getting the numerator: a[n_Integer]/; n >=2 := Numerator[f[n]] Generating the sequence : Table[a[n], {n, 2, 20}]
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CROSSREFS
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The Euler totient-function : A000010.
Sequence in context: A117066 A042984 A008780 this_sequence A003063 A124857 A126398
Adjacent sequences: A101989 A101990 A101991 this_sequence A101993 A101994 A101995
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KEYWORD
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frac,nonn
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AUTHOR
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Orges Leka (oleka(AT)students.uni-mainz.de), Dec 23 2004
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