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A067739
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Integers x such that for some integer y we have uphi(x) = uphi(y) = x-y, where uphi(n) = A047994(n) is the unitary totient function: If n = Product p_i^e_i, uphi(n) = Product (p_i^e_i - 1).
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5
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2, 60, 390, 840, 2310, 2910, 4386, 6090, 10374, 11220, 13860, 21882, 33654, 51090, 82680, 114294, 140910, 157080, 159530, 168630, 203190, 272514, 282170, 318318, 332010, 362670, 367080, 393414, 403130, 411990, 434070, 492882, 499590, 585390
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OFFSET
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1,1
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LINKS
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Donovan Johnson, Table of n, a(n) for n = 1..300
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MATHEMATICA
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uphi[n_] := Times@@(Power@@#-1&/@FactorInteger[n]); For[x=1, True, x++, If[uphi[y=x-(u=uphi[x])]==u, Print[{x, y}]]]
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CROSSREFS
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Cf. A047994, A067741.
Sequence in context: A078511 A141055 A048541 * A187626 A059934 A006333
Adjacent sequences: A067736 A067737 A067738 * A067740 A067741 A067742
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KEYWORD
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nonn
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AUTHOR
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Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp)
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EXTENSIONS
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Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Mar 07 2002
Offset corrected by Donovan Johnson, May 04 2013
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STATUS
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approved
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