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 A072724 #5 Nov 21 2013 12:47:50
%S A072724 1,4,8227,3427918353
%N A072724 Integers which are exactly the concatenation of the first m even numbers (A019520) divided by their sum (A002378 = m^2+m).
%C A072724 A probability argument suggests that this sequence may be finite.
%e A072724 a(1) = 2/2 =1; a(2) = 24/(2+4) = 4; a(3) = 246810/(2+4+6+8+10) = 8227; a(4) = 246810121416/(2+4+6+8+10+12+14+16).
%t A072724 With[{eds=Range[2,1500,2]},Select[Table[FromDigits[Flatten[ IntegerDigits/@ Take[eds,n]]]/Total[Take[eds,n]],{n,502}],IntegerQ]] (* _Harvey P. Dale_, Nov 29 2011 *)
%Y A072724 Cf. A067121, A072723, A072725.
%K A072724 base,nonn
%O A072724 1,2
%A A072724 _Henry Bottomley_, Jul 06 2002