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A162284
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Odd numbers n such that b(n) >= n and b(b(n)) >= n, where b(n) = A161942(n) = oddpart(sigma(n)).
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3
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1, 81, 18966025, 135187129, 164275489, 350561925, 445421025, 598047025, 649587169, 748733769, 850830561, 960362325, 1055925025, 1341097641, 1406175001, 1476326929, 1520766009, 1536248025, 1591004025, 1735566525
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OFFSET
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1,2
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COMMENTS
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Applying b a third time produces a smaller value for every number in this sequence up to 10^10, except 1.
Of the first 43 terms, only the following nine are not squares: 350561925, 960362325, 1591004025, 1735566525, 1753206525, 1831175325, 4558583925, 6745097205, 8766517725, and incidentally, all of them are terms of A228058. - Antti Karttunen, Jun 16 2019
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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