A210286 Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant = trace.

1, 3, 10, 18, 28, 42, 56, 74, 96, 118, 140, 170, 200, 234, 272, 302, 336, 386, 432, 482, 536, 578, 624, 690, 752, 810, 876, 938, 1000, 1082, 1156, 1234, 1328, 1402, 1476, 1558, 1632, 1730, 1840, 1926, 2008, 2122, 2228, 2338, 2464, 2554

Offset: 0

Author

Clark Kimberling, Mar 19 2012

Keywords

• nonn

Comments

See A210000 for a guide to related sequences.

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A210000.

Programs

Mathematica

a = 0; b = n; z1 = 45;
t[n_] := t[n] = Flatten[Table[w + z - 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, 0], {n, 0, z1}]    (* A210286 *)