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 A291458 #25 Dec 08 2019 12:25:29
%S A291458 27720,60480,65520,90720,98280,105840,115920,120120,120960,128520,
%T A291458 131040,143640,151200,163800,180180,191520,205920,207900,211680,
%U A291458 218400,229320,235620,241920,249480,264600,272160,289800,292320,312480,332640,360360,372960,393120,414960
%N A291458 Numbers n having a proper divisor d such that sigma(n) - k*d = k*n. Case k = 4.
%C A291458 Case k=2 are the admirable numbers (A111592).
%C A291458 Subset of A023198, A068404, A204831, A230608.
%H A291458 Amiram Eldar, <a href="/A291458/b291458.txt">Table of n, a(n) for n = 1..10000</a>
%e A291458 One of the proper divisors of 27720 is 360 and sigma(27720) - 4*360 = 112320 - 1440 = 110880 = 4*27720.
%e A291458 One of the proper divisors of 115920 is 144 and sigma(115920) - 4*144 = 464256 - 576 = 463680 = 4*115920.
%p A291458 with(numtheory): P:=proc(q,h) local a,k,n; for n from 1 to q do a:=sort([op(divisors(n))]);
%p A291458 for k from 1 to nops(a)-1 do if sigma(n)-h*a[k]=h*n then print(n); break; fi; od; od; end: P(10^9,4);
%t A291458 With[{k = 4}, Select[Range[5 * 10^5], Function[n, AnyTrue[Most@ Divisors@ n, DivisorSigma[1, n] - k # == k n &]]]] (* _Michael De Vlieger_, Aug 24 2017 *)
%t A291458 (* or *)
%t A291458 k=4; Select[Range[5*^5], (t = DivisorSigma[1, #]/k - #; #>t>0 && IntegerQ[t] && Mod[#, t] == 0) &] (* much faster, _Giovanni Resta_, Aug 25 2017 *)
%Y A291458 Cf. A000203, A023198, A068404, A111592, A204831, A230608, A291457, A291459.
%K A291458 nonn,easy
%O A291458 1,1
%A A291458 _Paolo P. Lava_, Aug 24 2017