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Search: id:A073544
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| A073544 |
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Numbers n such that 1/(1/phi(n) + 1/phi(n+1) + 1/phi(n+2) + 1/phi(n+3)) is an integer. |
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+0
1
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| 13, 75, 111, 144, 192, 558, 559, 1683, 2016, 3624, 7129, 10369, 11658, 18362, 19442, 19800, 19801, 32772, 47627, 60482, 82082, 133988, 143642, 229321, 291721, 312483, 352846, 390603, 395136, 436801, 465482, 600601, 711936, 806736, 819729
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OFFSET
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1,1
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EXAMPLE
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1/phi(75)+1/phi(76)+1/phi(77)+1/phi(78) = 1/40+1/36+1/60+1/24 = 1/9 so 75 is in the sequence.
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MATHEMATICA
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Select[Range[900000], IntegerQ[1/Sum[1/EulerPhi[ #+i], {i, 0, 3}]]&]
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CROSSREFS
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Sequence in context: A139070 A094421 A103968 this_sequence A051361 A114070 A005340
Adjacent sequences: A073541 A073542 A073543 this_sequence A073545 A073546 A073547
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 27 2002
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EXTENSIONS
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Edited by Dean Hickerson (dean(AT)math.ucdavis.edu), Sep 03 2002
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