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A070815
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Solutions to Phi[P[x]]-P[Phi[x]]=254=c are special multiples of 257, x=257k, where largest prime factors of factor k were observed from {2, 3, 5, 17}. See solutions to other even cases of c [=A070813]: A007283 for 0, A070004 for 2, A070814 for 14, A070816 for 65534.
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2
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257, 514, 771, 1028, 1285, 1542, 2056, 2570, 3084, 3855, 4112, 4369, 5140, 6168, 7710, 8224, 8738, 10280, 12336, 13107, 15420, 16448, 17476, 20560, 21845, 24672, 26214, 30840, 32896, 34952, 41120, 43690, 49344, 52428, 61680, 65535, 65792
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OFFSET
| 1,1
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EXAMPLE
| n=87380=4.5.17.257, P[n]=257,Phi[n]=65536, commutator[87380]=Phi[257]-P[65536]=256-2=254
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MATHEMATICA
| pf[x_] := Part[Reverse[Flatten[FactorInteger[x]]], 2] Do[s=EulerPhi[pf[n]]-pf[EulerPhi[n]]; If[Equal[s, 254], Print[{n, n/257, pf[n/257]}]], {n, 3, 1000000}] (*Terms of sequence are n*)
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CROSSREFS
| Cf. A000010, A006530, A070812, A070813, A000215, A070777, A070002-A070004, A007283.
Sequence in context: A105345 A060261 A158231 * A095321 A100633 A007765
Adjacent sequences: A070812 A070813 A070814 * A070816 A070817 A070818
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 09 2002
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