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A211413 Numbers m such that phi(m) is a power of the product of the distinct prime factors of m. 5
1, 4, 8, 16, 18, 32, 64, 108, 128, 250, 256, 512, 648, 1024, 2048, 2500, 3888, 4096, 6174, 8192, 16384, 23328, 25000, 32768, 41154, 65536, 101250, 131072, 139968, 250000, 259308, 262144, 524288, 839808, 1048576, 1542294, 2097152, 2500000, 2839714 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Sequence contains the numbers 2^(k+1), 2^k*3^(k+1) and 25*10^k, for k > 0.
a(226) > 10^18.
LINKS
EXAMPLE
m = 178726991395974 = 2*3*7^2*883^4 and phi(m) = 2^3*3^3*7^3*883^3.
MATHEMATICA
Select[Range[10^5], # == 1 || IntegerQ @ Log[Times @@ First /@ FactorInteger @ #, EulerPhi @ #] &]
CROSSREFS
Cf. A105261.
Subsequence of A055744.
Sequence in context: A055744 A141718 A195382 * A181310 A212110 A033310
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 10 2013
STATUS
approved

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Last modified April 25 10:01 EDT 2024. Contains 371967 sequences. (Running on oeis4.)