A211054 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n-1.

0, 1, 2, 6, 11, 26, 27, 66, 57, 109, 109, 182, 129, 319, 187, 332, 360, 497, 309, 714, 397, 839, 690, 842, 571, 1456, 821, 1156, 1126, 1663, 907, 2264, 1071, 2106, 1708, 1976, 1798, 3449, 1513, 2474, 2358, 3874, 1839, 4372, 2065, 3973

Offset: 0

Author

Clark Kimberling, Mar 31 2012

Keywords

• nonn

Comments

For a guide to related sequences, see A210000.

Examples

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

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..3000

Crossrefs

Cf. A210000, A211053.

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 - 1], {n, 1, z1}]  (* A211054 *)

Extensions

Offset corrected by Chai Wah Wu, Jan 04 2017