A096503 Euler-phi of these numbers is a decimal repdigit.

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, 134, 138, 178, 184, 223, 230, 276, 446, 669, 892, 1043, 1115, 1338, 1341, 1784, 2086, 2230, 2676, 2682, 446669, 666667, 893338, 895043, 902423, 1333334, 1340007, 1786676

Offset: 1

Author

Labos Elemer, Jul 12 2004

Keywords

• base
• nonn

Examples

			n=88888892, A000010(n)=44444444.
Regular solutions: if x=repdigit+1 is prime, then phi[x]=repdigit (see A028988).
		

Links

• T. D. Noe, Table of n, a(n) for n = 1..182
• D. Bressoud, CNT.m Computational Number Theory Mathematica package.

Crossrefs

Cf. A010785, A028988.

Programs

Mathematica

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 *)
Select[Range[2*10^5], Length@ Union@ IntegerDigits@ EulerPhi@ # == 1 &] (* Michael De Vlieger, Jul 02 2016 *)

PARI

isok(n) = d = digits(eulerphi(n)); vecmin(d) == vecmax(d); \\ Michel Marcus, Feb 25 2014