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 A104906 #5 Apr 25 2017 13:02:01
%S A104906 1,10,831,8310
%N A104906 Numbers n such that d(n)*reversal(n)=phi(n), where d(n) is number of positive divisors of n.
%C A104906 If n is a term of this sequence and gcd(10,n)=1 then 10*n is also in the sequence because reversal(10*n)=reversal(n); d(10)=phi(10) and both functions d & phi are multiplicative. No further terms up to 350000000.
%C A104906 a(5) > 10^12. - _Giovanni Resta_, Apr 25 2017
%e A104906 8310 is in the sequence because d(8310)=16; reversal(8310)=138;
%e A104906 phi(8310)=2208 & 16*138=2108.
%t A104906 reversal[n_]:= FromDigits[Reverse[IntegerDigits[n]]]; Do[If[DivisorSigma[0, n]*reversal[n] == EulerPhi[n], Print[n]], {n, 350000000}]
%Y A104906 Cf. A063903, A104904, A104905, A104907.
%K A104906 more,nonn
%O A104906 1,2
%A A104906 _Farideh Firoozbakht_, Apr 14 2005