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 A233465 #7 Mar 15 2014 17:57:23 %S A233465 1259196,1473381 %N A233465 Numbers n such that sigma(n) = reversal(2n). %C A233465 a(3) > 10^12. - _Giovanni Resta_, Mar 15 2014 %t A233465 rev[n_] := FromDigits@ Reverse@ IntegerDigits@n; Select[Range[2*10^6], DivisorSigma[1, #] == rev[2*#] &] (* _Giovanni Resta_, Mar 15 2014 *) %Y A233465 Cf. A000203, A004086, A233467. %K A233465 nonn,base,more,bref %O A233465 1,1 %A A233465 _Farideh Firoozbakht_, Mar 14 2014