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A319383
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Numbers k such that phi(k)^phi(k) == 1 (mod k^2).
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0
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OFFSET
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1,2
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COMMENTS
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All terms are cyclic numbers (A003277).
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LINKS
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MATHEMATICA
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Select[Range[20000], Divisible[EulerPhi[#]^EulerPhi[#] - 1, #^2] &] (* Vaclav Kotesovec, Oct 21 2018 *)
Join[{1}, Select[Range[1851*10^5], With[{c=EulerPhi[#]}, PowerMod[c, c, #^2] == 1&]]] (* Harvey P. Dale, Oct 09 2020 *)
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PROG
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(PARI) isok(n) = Mod(eulerphi(n), n^2)^eulerphi(n)==1;
for(n=1, 10000000, if(isok(n), print1(n, ", ")))
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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