A114068 sigma(n) + phi(n) is a fourth power.
110, 125, 609, 2047, 4895, 9819, 10149, 10367, 18974, 31269, 37032, 40662, 42032, 44238, 44835, 48125, 51459, 51535, 52487, 77425, 90090, 116633, 129846, 137865, 145299, 146566, 151438, 159565, 161614, 162334, 207710, 307327, 357116
Offset: 1
Keywords
Examples
sigma(110) + phi(110) = 256 = 4^4.
Links
- Donovan Johnson, Table of n, a(n) for n = 1..1000
Programs
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PARI
isok(n) = ispower(sigma(n) + eulerphi(n), 4); \\ Michel Marcus, Jan 09 2014