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 A258912 #12 Mar 09 2020 09:12:13
%S A258912 1178,1364,1408,1656,1767,1836,1922,1984,2108,2196,2328,2368,3162,
%T A258912 3336,3410,3996,4096,4123,4144,4278,4898,5064,5076,5084,5248,5456,
%U A258912 5488,5673,6014,6208,6504,6784,6816,7416,7998,8618,8896,9088,9184,9517,10048,10292,10864
%N A258912 Numbers k such that A000203(x) = k has more than one solution and they all share the same largest prime factor.
%C A258912 By definition this is a subsequence of A159886.
%C A258912 Pollack shows that the density of such integers relative to A002191 is 1.
%H A258912 Amiram Eldar, <a href="/A258912/b258912.txt">Table of n, a(n) for n = 1..10000</a>
%H A258912 Paul Pollack, <a href="https://doi.org/10.1007/978-3-319-22240-0_18">Remarks on fibers of the sum-of-divisors function</a>, Analytic number theory (volume in honor of H. Maier), M. Rassias and C. Pomerance, eds., Springer, 2015, <a href="http://pollack.uga.edu/preimages-maier3.pdf">alternative link</a>.
%e A258912 The pre-image of 1178 is [592, 925], and both have greatest prime factor 37, so 1178 is in the sequence.
%o A258912 (PARI) isok(n) = {my(v = select(x->sigma(x)==n, vector(n, i, i))); if (#v < 2, return (0)); vgpf = vector(#v, k, fvk = factor(v[k]); fvk[#fvk~,1]); vecmin(vgpf) == vecmax(vgpf);}
%Y A258912 Cf. A000203 (sum of divisors), A002191 (possible values of sum of divisors), A159886 (sigma(x)=n has more than one solution).
%K A258912 nonn
%O A258912 1,1
%A A258912 _Michel Marcus_, Jun 14 2015