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A192221
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Numbers n such that phi(n-2)=phi(n+2) where phi=A000010.
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1
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10, 16, 18, 22, 37, 54, 66, 93, 142, 150, 246, 294, 405, 457, 618, 630, 774, 803, 1013, 1026, 1110, 1146, 1254, 1272, 1297, 1458, 1590, 1686, 1822, 1830, 2032, 2166, 2454, 2625, 2646, 2662, 2694, 2934, 3030, 3218, 3323, 3510, 3990, 4266, 4342, 4374, 4614, 4806, 4854, 4950, 5182, 5286
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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Select[Range[3, 5000], EulerPhi[# - 2] == EulerPhi[# + 2] &] (* Alonso del Arte, Jun 28 2011 *)
Flatten[Position[Partition[EulerPhi[Range[5300]], 5, 1], _?(#[[1]] == #[[5]]&), 1, Heads -> False]]+2 (* Harvey P. Dale, Jul 01 2019 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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