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

0,5

Comments

For a guide to related sequences, see A210000.

Links

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

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 *)

Crossrefs

Cf. A210000.

Sequence in context: A362492 A139798 A359931 * A065762 A034009 A038732

Adjacent sequences: A211060 A211061 A211062 * A211064 A211065 A211066

Keyword

nonn

Author

Clark Kimberling, Mar 31 2012

Extensions

Offset corrected by Chai Wah Wu, Jan 10 2017

Status

approved