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 A204260 #5 Mar 30 2012 18:58:08
%S A204260 1,1,1,1,1,1,1,2,2,1,1,2,2,2,1,1,2,2,2,2,1,1,2,2,2,2,2,1,1,2,2,3,3,2,
%T A204260 2,1,1,2,3,3,3,3,3,2,1,1,2,3,3,3,3,3,3,2,1,1,2,3,3,3,3,3,3,3,2,1,1,2,
%U A204260 3,3,4,4,4,4,3,3,2,1,1,2,3,3,4,4,4,4,4,3,3,2,1,1,2,3,3,4,4,4,4
%N A204260 Symmetric matrix given by f(i,j)=ceiling(i*j/(i+j)) .
%e A204260 Northwest corner:
%e A204260 1 1 1 1 1 1 1 1
%e A204260 1 1 2 2 2 2 2 2
%e A204260 1 2 2 2 2 2 3 3
%e A204260 1 2 2 2 3 3 3 3
%e A204260 1 2 2 3 3 3 3 4
%e A204260 1 2 2 3 3 3 4 4
%t A204260 f[i_, j_] := Ceiling[i*j/(i + j)];
%t A204260 m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
%t A204260 TableForm[m[8]] (* 8x8 principal submatrix *)
%t A204260 Flatten[Table[f[i, n + 1 - i],
%t A204260 {n, 1, 12}, {i, 1, n}]] (* A204260 *)
%t A204260 Permanent[m_] :=
%t A204260 With[{a = Array[x, Length[m]]},
%t A204260 Coefficient[Times @@ (m.a), Times @@ a]];
%t A204260 Table[Permanent[m[n]], {n, 1, 14}] (* A204261 *)
%Y A204260 Cf. A204261.
%K A204260 nonn,tabl
%O A204260 1,8
%A A204260 _Clark Kimberling_, Jan 14 2012