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 A098218 #9 Oct 15 2013 22:32:34
%S A098218 35,121,231,327,535,1111,2047,2407,2911,3127,3327,20767,45967,64111,
%T A098218 75847,81607,103927,177367,202207,210767,224295,234607,275647,277807,
%U A098218 290911,295447,305887,308911,321407,333327,453911,475967,586127,1199327
%N A098218 Nonprime numbers whose cototient is a decimal repunits >1 from A002275.
%C A098218 It is believed that for every repdigit r>1, inverse(cototient(r)) has a solution, usually more than one. For r=1, primes are the solutions.
%H A098218 Donovan Johnson, <a href="/A098218/b098218.txt">Table of n, a(n) for n = 1..1000</a>
%e A098218 n=1111 and cototient(1111)=111. By accident, both n and its cototient are decimal repunits.
%t A098218 ta={{0}};Do[s=Length[u=Union[IntegerDigits[n-EulerPhi[n]]]]; If[Equal[s, 1]&&!PrimeQ[n]&&Equal[u, {1}], Print[{n, n-EulerPhi[n]}]; ta=Append[ta, n]], {n, 1, 100000}];ta=Delete[ta, 1];ta-EulerPhi[ta]
%Y A098218 Cf. A096503, A010785, A002275, A098216, A098217.
%K A098218 nonn,base
%O A098218 1,1
%A A098218 _Labos Elemer_, Oct 22 2004