A210291 Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant >n.

0, 0, 6, 40, 125, 323, 647, 1235, 2074, 3337, 5057, 7477, 10436, 14490, 19436, 25591, 33015, 42259, 52849, 65833, 80528, 97909, 117905, 141163, 166651, 196474, 229796, 267289, 308712, 355766, 406488, 464094, 526402, 595477, 670963

Offset: 0

Author

Clark Kimberling, Mar 20 2012

Keywords

• nonn

Comments

See A210000 for a guide to related sequences.

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A210000.

Programs

Mathematica

a = 0; b = n; z1 = 45;
t[n_] := t[n] = Flatten[Table[w*z - x*y, {w, a, b}, {x, a, b}, {y, a, b}, {z, a, b}]]
c[n_, k_] := c[n, k] = Count[t[n], k]
c1[n_, m_] := c1[n, m] = Sum[c[n, k], {k, 0, m}]
Table[c1[n, n^2] - c1[n, n], {n, 0, z1}]  (* A210291 *)