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A046642
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Numbers n such that n and number of divisors d(n) are relatively prime.
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2
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1, 3, 4, 5, 7, 11, 13, 15, 16, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47, 49, 51, 53, 55, 57, 59, 61, 64, 65, 67, 69, 71, 73, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 100, 101, 103, 105, 107, 109, 111, 113, 115, 119, 121, 123, 125, 127, 129, 131
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| A009191(a(n)) = 1.
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
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MATHEMATICA
| Select[ Range[200], CoprimeQ[#, DivisorSigma[0, #]] &] (* From Jean-François Alcover, Oct 20 2011 *)
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PROG
| (Haskell)
a046642 n = a046642_list !! (n-1)
a046642_list = map (+ 1) $ elemIndices 1 a009191_list
-- Reinhard Zumkeller, Aug 14 2011
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CROSSREFS
| Cf. A009191, A009230.
Sequence in context: A091428 A047499 A082378 * A140826 A081735 A107036
Adjacent sequences: A046639 A046640 A046641 * A046643 A046644 A046645
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KEYWORD
| nonn,nice,easy
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AUTHOR
| Labos Elemer (LABOS(AT)ana.sote.hu)
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