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%I #21 Jul 02 2016 22:53:35
%S 1,2,3,4,5,6,7,8,9,10,12,14,15,16,18,20,23,24,30,46,67,69,89,92,115,
%T 134,138,178,184,223,230,276,446,669,892,1043,1115,1338,1341,1784,
%U 2086,2230,2676,2682,446669,666667,893338,895043,902423,1333334,1340007,1786676
%N Euler-phi of these numbers is a decimal repdigit.
%H T. D. Noe, <a href="/A096503/b096503.txt">Table of n, a(n) for n = 1..182</a>
%H D. Bressoud, <a href="http://www.macalester.edu/~bressoud/books/CNT.m">CNT.m</a> Computational Number Theory Mathematica package.
%e n=88888892, A000010(n)=44444444.
%e Regular solutions: if x=repdigit+1 is prime, then phi[x]=repdigit (see A028988).
%t Needs["CNT`"]; t = {PhiInverse[1]}; Do[n = FromDigits[Table[i, {j}]]; AppendTo[t, PhiInverse[n]], {j, 18}, {i, 2, 8, 2}]; t2 = Union[Flatten[t]]; t (* _T. D. Noe_, Feb 25 2014 *)
%t Select[Range[2*10^5], Length@ Union@ IntegerDigits@ EulerPhi@ # == 1 &] (* _Michael De Vlieger_, Jul 02 2016 *)
%o (PARI) isok(n) = d = digits(eulerphi(n)); vecmin(d) == vecmax(d); \\ _Michel Marcus_, Feb 25 2014
%Y Cf. A010785, A028988.
%K base,nonn
%O 1,2
%A _Labos Elemer_, Jul 12 2004
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