A211063 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant >=3n.

0, 0, 0, 0, 8, 38, 122, 284, 589, 1080, 1848, 2933, 4515, 6577, 9366, 12888, 17444, 22928, 29864, 37986, 48057, 59656, 73413, 89307, 108002, 129068, 153386, 180636, 212111, 246683, 286126, 329135, 378047, 431242, 490425, 555118

Offset: 0

Author

Clark Kimberling, Mar 31 2012

Keywords

• nonn

Comments

For a guide to related sequences, see A210000.

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..2000

Crossrefs

Cf. A210000.

Programs

Mathematica

a = 1; b = n; z1 = 35;
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]
s[n_, m_] := s[n, m] = Sum[c[n, k], {k, 1, m}]
Table[s[n,n^2]-s[n,3n-1],{n,1,z1}] (* A211063 *)

Extensions

Offset corrected by Chai Wah Wu, Jan 10 2017