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%I #13 Nov 29 2013 09:56:31
%S 44722206,69067317,460647525,485700768,427528099084
%N Composite solutions to the equation phi(x)+sigma(x) = 2*reversal(x).
%C For a prime p we have phi(p)+sigma(p) = 2*reversal(p) iff p is a palindrome.
%C a(6) > 10^12. - _Giovanni Resta_, Nov 03 2012
%e 485700768 is in the sequence because 485700768 is composite and phi(485700768)+sigma(485700768) = 1734015168 = 2*867007584.
%t Do[a=FromDigits[Reverse[IntegerDigits[n]]];If[a>n&&EulerPhi[n]+ DivisorSigma[1,n]==2a,Print[n]],{n,250000000}] (* _Farideh Firoozbakht_, Nov 26 2013 *)
%Y Cf. A000010, A000203, A004086, A130000, A230020.
%K hard,more,nonn,base
%O 1,1
%A _Farideh Firoozbakht_, Jun 09 2007
%E a(5) from _Giovanni Resta_, Nov 03 2012
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