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A076529
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Numbers k for which phi(k) = phi(k+1) - phi(k-1).
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3
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2, 4, 6, 10, 16, 22, 36, 40, 46, 100, 136, 232, 256, 856, 1036, 1296, 1540, 1600, 2016, 4336, 6526, 9178, 14400, 16096, 30496, 55386, 61132, 62800, 65536, 72580, 77616, 110176, 152650, 179296, 244966, 299650, 603460, 619696, 686736, 1876726, 2841916, 3058210
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OFFSET
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1,1
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LINKS
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EXAMPLE
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phi(22) = 10; phi(23) = 22; phi(21) = 12 and 10 = 22 - 12; hence 22 is a term of the sequence.
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MATHEMATICA
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Select[Range[2, 10^5], EulerPhi[#] == EulerPhi[#+1] - EulerPhi[#-1] &]
Flatten[ Position[Partition[EulerPhi[Range[31*10^5]], 3, 1], _?(#[[2]] == #[[3]] -#[[1]]&), 1, Heads->False]]+1 (* Harvey P. Dale, Dec 28 2017 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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