This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A096503 #21 Jul 02 2016 22:53:35 %S A096503 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 A096503 134,138,178,184,223,230,276,446,669,892,1043,1115,1338,1341,1784, %U A096503 2086,2230,2676,2682,446669,666667,893338,895043,902423,1333334,1340007,1786676 %N A096503 Euler-phi of these numbers is a decimal repdigit. %H A096503 T. D. Noe, <a href="/A096503/b096503.txt">Table of n, a(n) for n = 1..182</a> %H A096503 D. Bressoud, <a href="http://www.macalester.edu/~bressoud/books/CNT.m">CNT.m</a> Computational Number Theory Mathematica package. %e A096503 n=88888892, A000010(n)=44444444. %e A096503 Regular solutions: if x=repdigit+1 is prime, then phi[x]=repdigit (see A028988). %t A096503 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 A096503 Select[Range[2*10^5], Length@ Union@ IntegerDigits@ EulerPhi@ # == 1 &] (* _Michael De Vlieger_, Jul 02 2016 *) %o A096503 (PARI) isok(n) = d = digits(eulerphi(n)); vecmin(d) == vecmax(d); \\ _Michel Marcus_, Feb 25 2014 %Y A096503 Cf. A010785, A028988. %K A096503 base,nonn %O A096503 1,2 %A A096503 _Labos Elemer_, Jul 12 2004