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Search: id:A137733
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| A137733 |
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Numbers n such that sigma(2 phi(n)) = 2 sigma(n). |
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+0
1
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| 2318, 2806, 5734, 5937, 7198, 8097, 10126, 11295, 11818, 13054, 17324, 20374, 21838, 22947, 27694, 29145, 32086, 33826, 35074, 38997, 42334, 42458, 43798, 46726, 54825, 56974, 58438, 61366, 66202, 68686, 71614, 86762, 86924, 87435
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OFFSET
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1,1
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REFERENCES
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Jean-Marie De Koninck and Florian Luca, Positive Integers $n$ Such That $\sigma(\phi(n))=\sigma(n)$, Journal of Integer Sequences, Paper No. 08.1.5, 2008.
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LINKS
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De Koninck and Luca paper
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EXAMPLE
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a(1) = 2318, because this is the smallest integer such that sigma(2 phi(n)) = 2 sigma(n).
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CROSSREFS
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Sequence in context: A132214 A133538 A075668 this_sequence A119735 A115933 A043440
Adjacent sequences: A137730 A137731 A137732 this_sequence A137734 A137735 A137736
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KEYWORD
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nonn
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AUTHOR
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Jeffrey Shallit (shallit(AT)graceland.uwaterloo.ca), Feb 09 2008; definition corrected Feb 09 2008
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