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 A227760 #6 Aug 08 2013 15:15:26
%S A227760 5,6,8,10,11,12,14,15,17,19,20,21,22,23,24,26,27,28,29,30,32,33,34,35,
%T A227760 38,39,40,41,42,44,45,46,47,48,51,52,53,54,55,56,57,58,59,60,62,63,65,
%U A227760 66,68,69,70,71,72,74,75,76,77,78,79,80,82,83,84,85,86,87
%N A227760 Numbers n such that A227758(n) = sigma(sigma(n)) - sigma(n) - n > 0, where sigma(n) = A000203(n) = sum of the divisors of n.
%C A227760 Numbers n such that A051027(n) - A000203(n) - n < 0, where A000203(n) = sum of the divisors of n , A051027(n) = A000203(A000203(n)) = sigma(sigma(n)) = sum of the divisors of the sum of the divisors of n.
%C A227760 Conjecture: a(n) = complement of union A000668 and A227759, where A000668 = Mersenne primes, A227759 = numbers n such that sigma(sigma(n)) - sigma(n) - n < 0.
%F A227760 A227758(a(n)) > 0.
%e A227760 Number 15 is in sequence because sigma(sigma(15)) - sigma(15) - 15 = 60 - 24 - 15 = 21 > 0.
%t A227760 sgmaQ[n_]:=Module[{s=DivisorSigma[1,n]},Positive[DivisorSigma[1,s]-s-n]]; Select[Range[100],sgmaQ] (* _Harvey P. Dale_, Aug 08 2013 *)
%Y A227760 Cf. A000203, A051027, A000668, A227759, A227758.
%K A227760 nonn
%O A227760 1,1
%A A227760 _Jaroslav Krizek_, Jul 29 2013