OFFSET
1,1
COMMENTS
EXAMPLE
Northwest corner:
2 1 2 1 2 1 2 1
1 3 1 1 3 1 1 3
2 1 4 1 2 1 4 1
1 1 1 5 1 1 1 1
2 3 2 1 6 1 2 3
1 1 1 1 1 7 1 1
MATHEMATICA
f[i_, j_] := GCD[i + 1, j + 1];
m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
TableForm[m[8]] (* 8 X 8 principal submatrix *)
Flatten[Table[f[i, n + 1 - i],
{n, 1, 15}, {i, 1, n}]] (* A204030 *)
p[n_] := CharacteristicPolynomial[m[n], x];
c[n_] := CoefficientList[p[n], x]
TableForm[Flatten[Table[p[n], {n, 1, 10}]]]
Table[c[n], {n, 1, 12}]
Flatten[%] (* A204111 *)
TableForm[Table[c[n], {n, 1, 10}]]
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Jan 11 2012
STATUS
approved