A204429 - OEIS

%I #13 Oct 25 2021 16:41:46

%S 1,0,0,2,2,2,1,1,1,1,0,0,0,0,0,2,2,2,2,2,2,1,1,1,1,1,1,1,0,0,0,0,0,0,

%T 0,0,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,2,2,

%U 2,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0

%N Symmetric matrix: f(i,j)=(2*i + 2*j) mod 3, by antidiagonals.

%C A block matrix over {0,1,2}.  See A204263 for a guide to related matrices and permanents.

%e Northwest corner:

%e 1 0 2 1 0 2

%e 0 2 1 0 2 1

%e 2 1 0 2 1 0

%e 1 0 2 1 0 2

%e 0 2 1 0 2 1

%e 2 1 0 2 1 0

%t f[i_, j_] := Mod[2 i + 2 j, 3];  (* symmetric *)

%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],  {n, 1, 14}, {i, 1, n}]]

%Y Cf. A204430, A204263.

%K nonn,tabl

%O 1,4

%A _Clark Kimberling_, Jan 15 2012

%E Definition corrected by _Georg Fischer_, Oct 25 2021