A211053 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n.

0, 2, 7, 16, 23, 50, 45, 93, 99, 150, 117, 283, 167, 308, 336, 443, 289, 654, 369, 803, 658, 762, 543, 1392, 779, 1092, 1086, 1563, 879, 2160, 1011, 2038, 1652, 1888, 1758, 3323, 1445, 2386, 2302, 3730, 1795, 4220, 1989, 3889, 3737

Offset: 1

Author

Clark Kimberling, Mar 31 2012

Keywords

• nonn

Comments

For a guide to related sequences, see A210000.

Examples

			a(2) counts these 2 matrices:
2 1.....2 2
2 2.....1 2
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..3000

Crossrefs

Cf. A210000.

Programs

Mathematica

a = 1; 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]
Table[c[n, n], {n, 1, z1}]  (* A211053 *)