%I
%S 1,0,0,1,0,1,0,1,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,1,0,
%T 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,
%U 0,1,0,1,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0
%N Symmetric matrix based on f(i,j)=(1 if max(i,j) is odd, and 0 otherwise), by antidiagonals.
%C A204171 represents the matrix M given by f(i,j)=(1 if max(i,j) is odd, and 0 otherwise) for i>=1 and j>=1. See A204172 for characteristic polynomials of principal submatrices of M, with interlacing zeros. See A204016 for a guide to other choices of M.
%e Northwest corner:
%e 1 0 1 0 1 0 1 0
%e 0 0 1 0 1 0 1 0
%e 1 1 1 0 1 0 1 0
%e 0 0 0 0 1 0 1 0
%e 1 1 1 1 1 0 1 0
%t f[i_, j_] := If[Mod[Max[i, j], 2] == 1, 1, 0]
%t m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
%t TableForm[m[8]] (* 8x8 principal submatrix *)
%t Flatten[Table[f[i, n + 1  i],
%t {n, 1, 15}, {i, 1, n}]] (* A204171 *)
%t p[n_] := CharacteristicPolynomial[m[n], x];
%t c[n_] := CoefficientList[p[n], x]
%t TableForm[Flatten[Table[p[n], {n, 1, 10}]]]
%t Table[c[n], {n, 1, 12}]
%t Flatten[%] (* A204172 *)
%t TableForm[Table[c[n], {n, 1, 10}]]
%Y Cf. A204172, A204016, A202453.
%K nonn,tabl
%O 1
%A _Clark Kimberling_, Jan 12 2012
