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 A162692 #4 Mar 31 2012 12:38:25
%S A162692 21,28,70,84,168,364,756
%N A162692 Strictly positive numbers n such that 28*n/(28+n) are integers.
%C A162692 The 28th row of A127730.
%C A162692 The ansatz 28*n/(28+n)=j (any integer j) yields n=28*j/(28-j) which demonstrates that the sequence is finite if n>=0. [R. J. Mathar, Jul 13 2009]
%t A162692 f[a_,b_]:=(a*b)/(a+b); a=28;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]],AppendTo[lst,n]],{n,9!}];lst
%Y A162692 Cf. A162688, A162689, A162690, A162691
%Y A162692 Cf. A127730. [From _Franklin T. Adams-Watters_, Aug 07 2009]
%K A162692 nonn,fini,full
%O A162692 1,1
%A A162692 _Vladimir Joseph Stephan Orlovsky_, Jul 10 2009
%E A162692 Edited by _R. J. Mathar_, Jul 13 2009