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 A048147 #9 May 06 2013 00:56:40
%S A048147 0,1,1,4,2,4,9,5,5,9,16,10,8,10,16,25,17,13,13,17,25,36,26,20,18,20,
%T A048147 26,36,49,37,29,25,25,29,37,49,64,50,40,34,32,34,40,50,64,81,65,53,45,
%U A048147 41,41,45,53,65,81,100,82,68,58,52,50,52,58,68
%N A048147 Array T read by diagonals; T(i,j) = i^2 + j^2.
%C A048147 For any i,j >=0 a(i)*a(j) is a member of this sequence, since (a^2 + b^2)*(c^2 + d^2) = (a*c + b*d)^2 + (a*d - b*c)^2. - _Boris Putievskiy_, May 05 2013
%e A048147 Diagonals (each starting on row 1): {0}; {1,1}; {4,2,4}; ...
%Y A048147 Cf. A006331.
%K A048147 nonn,tabl
%O A048147 0,4
%A A048147 _Clark Kimberling_