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 A291791 #12 Sep 17 2017 19:58:14
%S A291791 4,8,9,12,14,15,16,18,20,24,25,28,32,33,34,35,36,42,48,49,50,54,55,56,
%T A291791 62,63,64,69,70,72,76,77,78,81,84,85,86,87,88,90,93,94,95,96,98,99,
%U A291791 100,102,104,105,108,110,111
%N A291791 Numbers n whose trajectory under the iteration of k -> (sigma(k)+phi(k))/2 reaches a fraction.
%C A291791 It would be nice to have an independent characterization of these numbers (not involving the map in the definition).
%H A291791 Hugo Pfoertner, <a href="/A291791/b291791.txt">Table of n, a(n) for n = 1..126</a>
%Y A291791 Union of A028982 \ {1,2} and A290001. Also the complement of A289997.
%Y A291791 Cf. A000010, A000203.
%K A291791 nonn
%O A291791 1,1
%A A291791 _N. J. A. Sloane_, Sep 03 2017
%E A291791 B-file shortened by _N. J. A. Sloane_, Sep 17 2017