A210289 Number of 2 X 2 matrices with all elements in {0,1,...,n} and permanent = (trace)^2.

1, 5, 9, 15, 25, 29, 35, 53, 63, 81, 85, 89, 107, 141, 159, 165, 193, 197, 215, 261, 271, 323, 327, 331, 349, 389, 423, 461, 529, 533, 539, 617, 645, 651, 655, 673, 727, 817, 863, 959, 969, 973, 1025, 1131, 1141, 1159

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^2 + z^2 + 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}]  (* A210289 *)