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 A027449 #13 May 06 2022 07:55:33
%S A027449 3,5,7,27,22,130,225,595,532,5292,4830,57750,53460,49764,93093,
%T A027449 1486485,1401400,25185160,23891868,22724988,21666840,476166600,
%U A027449 455885430,2186310126,2100505176,6063549800,5842908500,163495203300,157949751960,4735815444360
%N A027449 Second diagonal of A027446.
%F A027449 Numerators of sequence a[ n, n-1 ] in (a[ i, j ])^2 where a[ i, j ] = 1/i if j<=i, 0 if j>i.
%t A027449 rows = 31;
%t A027449 M = MatrixPower[Table[If[j <= i, 1/i, 0], {i, 1, rows}, {j, 1, rows}], 2];
%t A027449 T = Table[M[[n]]*LCM @@ Denominator[M[[n]]], {n, 1, rows}];
%t A027449 a[n_] := T[[n, n-1]];
%t A027449 Table[a[n], {n, 2, rows}] (* _Jean-François Alcover_, May 06 2022 *)
%Y A027449 Cf. A027446.
%K A027449 nonn
%O A027449 2,1
%A A027449 _Olivier Gérard_
%E A027449 More terms from _Sean A. Irvine_, Nov 04 2019