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Search: id:A091495
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| A091495 |
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Odd, squarefree n such that n/phi(n) > 2, where phi is Euler's totient function. |
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+0
2
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| 105, 165, 195, 1155, 1365, 1785, 1995, 2145, 2415, 2805, 3003, 3045, 3135, 3255, 3315, 3705, 3795, 3885, 3927, 4305, 4389, 4485, 4515, 4641, 4785, 4845, 4935, 5115, 5187, 5313, 5565, 5655, 5865, 6045, 6105, 6195, 6405, 6555, 6765, 7035, 7095, 7215
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Apparently the squarefree members of the sequence A036798. Note that 105, 165 and 195 are the only terms having 3 prime factors. Also note that all the numbers listed above have 3 as a factor. The smallest number of this form not divisible by 3 is 37182145 = 5*7*11*13*17*19*23.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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MATHEMATICA
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lst={}; Do[f=FactorInteger[n]; s=Times@@Last/@f; If[s==1&&Times@@(1-1/(First/@f))<1/2, AppendTo[lst, n]], {n, 3, 10000, 2}]; lst
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CROSSREFS
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Cf. A036798.
Sequence in context: A076762 A036798 A119434 this_sequence A046405 A128278 A128284
Adjacent sequences: A091492 A091493 A091494 this_sequence A091496 A091497 A091498
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Jan 15 2004
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