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A173941
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Numbers k such that tau(lambda(k)) = lambda(tau(k)).
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1
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1, 2, 4, 6, 8, 12, 24, 100, 168, 180, 264, 300, 468, 552, 684, 1100, 1128, 1260, 1416, 1848, 1992, 2340, 2568, 3276, 3300, 3600, 3864, 4008, 4296, 4788, 4920, 5208, 5448, 6072, 6312, 7056, 7224, 7896, 8184, 8328, 8616, 9192, 9912
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OFFSET
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1,2
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COMMENTS
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Previous name: tau(lambda(n)) = lambda(tau(n)) for the sequential application of the number of divisors of n and Carmichael lambda function.
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LINKS
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MAPLE
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with(numtheory): for n from 1 to 10000 do:if tau(lambda(n))=lambda(tau(n))then
printf(`%d, `, n):else fi:od:
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MATHEMATICA
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Cases[Range[1000], k_ /; DivisorSigma[0, CarmichaelLambda[k]] == CarmichaelLambda[DivisorSigma[0, k]]]
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PROG
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(PARI) lambda(n) = lcm(znstar(n)[2]); \\ A002322
isok(k) = numdiv(lambda(k)) == lambda(numdiv(k)); \\ Michel Marcus, Jul 17 2019
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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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