A211055 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n+1.

0, 1, 4, 9, 20, 23, 51, 55, 88, 79, 181, 121, 214, 222, 323, 227, 484, 299, 605, 488, 604, 457, 1102, 623, 902, 876, 1269, 769, 1754, 893, 1728, 1370, 1634, 1436, 2811, 1303, 2100, 1964, 3184, 1637, 3622, 1823, 3403, 3171, 3138

Offset

1,3

Comments

For a guide to related sequences, see A210000.

Links

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

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}]   (* A211055 *)

Crossrefs

Cf. A210000, A211053.

Sequence in context: A241351 A023377 A187408 * A336025 A308482 A136769

Adjacent sequences: A211052 A211053 A211054 * A211056 A211057 A211058

Keyword

nonn

Author

Clark Kimberling, Mar 31 2012

Status

approved