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A082955 Numbers k such that sigma(k*phi(k)) = sigma(k)^2. 1
1, 87, 1257, 42921, 65307, 68037, 89067, 112803, 116619, 186231, 252417, 350283, 356259, 380559, 435993, 477723, 492771, 527781, 635259, 672051, 708111, 866379, 991479, 1062723, 1078509, 1347699, 1352199, 1353873, 1449363, 1561431, 1838019 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[2000000], DivisorSigma[1, # EulerPhi[#]]== DivisorSigma[1, #]^2&] (* Harvey P. Dale, Mar 27 2011 *)
PROG
(PARI) for(n=1, 2000000, if(sigma(n*eulerphi(n))==sigma(n)^2, print1(n, ", ")))
CROSSREFS
Sequence in context: A093287 A231218 A186054 * A201154 A171344 A200533
KEYWORD
nonn
AUTHOR
Benoit Cloitre, May 26 2003
EXTENSIONS
More terms from Rick L. Shepherd, Jun 05 2003
STATUS
approved

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Last modified June 18 08:27 EDT 2024. Contains 373472 sequences. (Running on oeis4.)