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A058817
Even cototient numbers.
2
0, 2, 4, 6, 8, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 36, 38, 40, 42, 44, 46, 48, 54, 56, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 88, 90, 92, 94, 96, 98, 102, 104, 106, 108, 110, 112, 114, 118, 120, 124, 126, 128, 132, 136, 138, 140, 142, 144, 148, 150, 152
OFFSET
1,2
LINKS
FORMULA
Even terms of A063742.
EXAMPLE
88 is here because it is the cototient of 120: 88 = 120-phi(120) = 120-32 = 88.
MATHEMATICA
With[{max = 300}, Union@ Select[Table[n - EulerPhi[n], {n, 1, max^2}], # < max && EvenQ[#] &]] (* Amiram Eldar, Jan 12 2024 *)
KEYWORD
nonn
AUTHOR
Labos Elemer, Jan 04 2001
EXTENSIONS
Offset corrected by Donovan Johnson, Nov 17 2013
a(1) = 0 inserted by Amiram Eldar, Jan 12 2024
STATUS
approved