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 A204114 #9 Aug 02 2019 04:12:40
%S A204114 1,1,1,1,3,1,1,1,1,1,1,1,4,1,1,1,1,1,1,1,1,1,3,1,7,1,3,1,1,1,2,1,1,2,
%T A204114 1,1,1,1,1,1,11,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,4,1,1,18,1,1,4,3,1,1,
%U A204114 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,29,1,1,1,1,1,1,1,1,2,1,1,2,1
%N A204114 Symmetric matrix based on f(i,j) = gcd(L(i), L(j)), where L=A000032 (Lucas numbers), by antidiagonals.
%C A204114 A204114 represents the matrix M given by f(i,j) = gcd(L(i+1), L(j+1)) for i >= 1 and j >= 1. See A204115 for characteristic polynomials of principal submatrices of M, with interlacing zeros. See A204016 for a guide to other choices of M.
%e A204114 Northwest corner:
%e A204114 1 1 1 1 1
%e A204114 1 3 1 1 1
%e A204114 1 1 4 1 1
%e A204114 1 1 1 7 1
%e A204114 1 1 1 1 11
%t A204114 u[n_] := LucasL[n]
%t A204114 f[i_, j_] := GCD[u[i], u[j]];
%t A204114 m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
%t A204114 TableForm[m[8]] (* 8 X 8 principal submatrix *)
%t A204114 Flatten[Table[f[i, n + 1 - i],
%t A204114 {n, 1, 15}, {i, 1, n}]] (* A204114 *)
%t A204114 p[n_] := CharacteristicPolynomial[m[n], x];
%t A204114 c[n_] := CoefficientList[p[n], x]
%t A204114 TableForm[Flatten[Table[p[n], {n, 1, 10}]]]
%t A204114 Table[c[n], {n, 1, 12}]
%t A204114 Flatten[%] (* A204115 *)
%t A204114 TableForm[Table[c[n], {n, 1, 10}]]
%Y A204114 Cf. A204115, A204016, A202453.
%K A204114 nonn,tabl
%O A204114 1,5
%A A204114 _Clark Kimberling_, Jan 11 2012