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Search: id:A061366
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A061366 Numbers n such that phi(n)+sigma(n) is a perfect cube. +0
1
99, 814, 1371, 2047, 2883, 5816, 6105, 6851, 10718, 16744, 19390, 19651, 20080, 20115, 20820, 22015, 22165, 22550, 23035, 25976, 30090, 31999, 32130, 34479, 36492, 36865, 37043, 39942, 40347, 42591, 44475, 48667, 52377, 54213, 54321 (list; graph; listen)
OFFSET

1,1

EXAMPLE

phi(99)+sigma(99) = 60+156 = 216 = 6^3, so 99 is a term of the sequence.

MATHEMATICA

Select[Range[10^5], IntegerQ[(EulerPhi[ # ] + DivisorSigma[1, # ])^(1/3)] &]

CROSSREFS

Sequence in context: A027579 A157659 A154359 this_sequence A135219 A093299 A074786

Adjacent sequences: A061363 A061364 A061365 this_sequence A061367 A061368 A061369

KEYWORD

nonn

AUTHOR

Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 13 2002

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Last modified December 5 23:38 EST 2009. Contains 170428 sequences.


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