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 A162823 #9 Mar 14 2020 19:06:48
%S A162823 6,14,21,24,28,30,33,35,36,38,39,40,41,42,43,44,45,46,48,49,51,54,56,
%T A162823 60,63,70,78,84,91,105,126,140,168,189,238,294,336,483,630,924,1806
%N A162823 Positive numbers k such that 42*k/(42-k) are integers.
%C A162823 The number k=42 is explicitly included, treating the result of division through zero as an integer.
%C A162823 Row 42 of A191973.
%p A162823 for m from 1 to 1806 do if(m=42 or m*42 mod (m-42) = 0)then printf("%d, ", m): fi: od: # _Nathaniel Johnston_, Jun 22 2011
%t A162823 f[a_,b_]:=(a*b)/(a-b); a=42;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst
%t A162823 Join[{42},Select[Range[2000],IntegerQ[(42#)/(42-#)]&]]//Quiet//Sort (* _Harvey P. Dale_, Mar 14 2020 *)
%Y A162823 Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694, A162817, A162818, A162819, A162820, A162821, A162822, A191973.
%K A162823 nonn,fini,full,easy
%O A162823 1,1
%A A162823 _Vladimir Joseph Stephan Orlovsky_, Jul 13 2009
%E A162823 Keywords fini,full added by _R. J. Mathar_, Jul 31 2009