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A230238
Numbers n such that phi(sigma(n)) + sigma(phi(n)) is the mean value of phi(n) and sigma(n).
2
6, 37716, 58710, 120930, 1269432, 2663850, 3349170, 3995244, 4353426, 5468424, 7191072, 7437960, 7564128, 7613892, 8354610, 8810490, 10309410, 11917620, 13573500, 21970980, 23877450, 24712350, 38801790, 49394556, 56208264, 56809578, 57339150, 66379170, 77966616, 91549710, 93657564
OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..111 (terms < 3*10^10)
MATHEMATICA
Do[If[DivisorSigma[1, n]+EulerPhi[n]==2(EulerPhi[DivisorSigma[1, n]]+DivisorSigma[1, EulerPhi[n]]), Print[n]], {n, 100000000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Farideh Firoozbakht, Oct 16 2013
STATUS
approved