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Search: id:A076532
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| A076532 |
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Numbers n such that sopf(sigma(n)) = sigma(sopf(n)), where sopf(x) = sum of the distinct prime factors of x. |
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+0
8
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| 2, 90, 425, 490, 605, 630, 726, 735, 750, 816, 2250, 2695, 3185, 3234, 3420, 3822, 4176, 5096, 5250, 6591, 7644, 8470, 9100, 9425, 10296, 10780, 11616, 11638, 12321, 15750, 16940, 18096, 22736, 23276, 25578, 27360, 27783, 28500, 31900, 36400
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OFFSET
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1,1
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EXAMPLE
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sopf(sigma(90)) = sopf(234) = 18; sigma(sopf(90)) = sigma(10) = 18, hence 90 is a term of the sequence.
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MATHEMATICA
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p[n_] := Apply[Plus, Transpose[FactorInteger[n]][[1]]]; Select[Range[2, 10^4], p[DivisorSigma[1, # ]] == DivisorSigma[1, p[ # ]] &]
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CROSSREFS
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Cf. A008472, A075565, A075784, A075846, A076525, A076527, A076531, A076533.
Sequence in context: A023302 A041967 A024239 this_sequence A157064 A058527 A138583
Adjacent sequences: A076529 A076530 A076531 this_sequence A076533 A076534 A076535
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 18 2002
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EXTENSIONS
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Edited and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 13 2005
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