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 A146566 #35 Oct 04 2024 00:22:22
%S A146566 3,4,6,8,12,18,24,36,40,60,84,156,180,600
%N A146566 Numbers k such that k*sigma_0(k) is divisible by (k - sigma_0(k)).
%C A146566 No other term < 10000000. - _Michel Marcus_, Jun 02 2013
%C A146566 No other term multiple of 12 below 10^9. - _M. F. Hasler_, Apr 16 2022
%F A146566 A352483(a(n)) = 1. - _Bernard Schott_, Mar 23 2022
%t A146566 nsiQ[n_]:=Module[{s=DivisorSigma[0,n]},IntegerQ[(n*s)/(n-s)]]; Select[ Range[3,600],nsiQ] (* _Harvey P. Dale_, Dec 05 2019 *)
%o A146566 (PARI) isok(n) = {my(nd = numdiv(n)); type(n*nd/(n-nd)) == "t_INT"} \\ _Michel Marcus_, Jun 02 2013
%o A146566 (PARI) is_A146566(n,d=numdiv(n))={n*d%(n-d)==0} \\ _M. F. Hasler_, Apr 16 2022
%Y A146566 Cf. A000005, A049820, A352483.
%K A146566 nonn,more
%O A146566 1,1
%A A146566 _Ctibor O. Zizka_, Nov 01 2008
%E A146566 Corrected and extended by _Michel Marcus_, Jun 02 2013