A210366 Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant >=n.

1, 3, 18, 61, 168, 368, 749, 1310, 2235, 3493, 5291, 7640, 10869, 14711, 19860, 26051, 33623, 42618, 53725, 66280, 81577, 98739, 118847, 141800, 168435, 197406, 231100, 268595, 310617, 356763, 409136, 465231, 528830, 597397, 673127

Offset

0,2

Comments

See A210000 for a guide to related sequences.

Links

Table of n, a(n) for n=0..34.

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 - 1], {n, 0, z1}](* A210366 *)

Crossrefs

Cf. A210000.

Sequence in context: A327768 A074439 A299031 * A000648 A235988 A253942

Adjacent sequences: A210363 A210364 A210365 * A210367 A210368 A210369

Keyword

nonn

Author

Clark Kimberling, Mar 20 2012

Status

approved