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 A333263 #4 Mar 13 2020 20:47:07 %S A333263 5,447,700,3122,20649,25816,70221,205701,408624,2574176,3827656, %T A333263 4753563,12129928,118200807 %N A333263 Numbers k such that the sum of iterations of the alternating sum of divisors function A071324 starting from k is equal to 2*k. %e A333263 5 is a term since the iterations of A071324 with a starting value of 5 give A071324(5) = 4, A071324(4) = 3, A071324(3) = 2, and A071324(2) = 1, whose sum is 4 + 3 + 2 + 1 = 10 = 2 * 5. %t A333263 f[n_] := Plus @@ (-(d = Divisors[n])*(-1)^(Range[Length[d],1,-1])); seqQ[n_]:=Plus @@ FixedPointList[f,n] == 3n + 1; Select[Range[10000], seqQ] %Y A333263 Cf. A071324, A331017, A333262. %K A333263 nonn,more %O A333263 1,1 %A A333263 _Amiram Eldar_, Mar 13 2020