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A211032 Number of 2 X 2 matrices having all elements in {0,1,...,n} and determinant in the open interval (-n,n).

%I A211032 #7 Jan 10 2017 22:07:26
%S A211032 10,45,134,289,560,903,1476,2091,3014,4059,5456,6823,8994,10905,13434,
%T A211032 16275,19740,22871,27440,31327,36778,42147,48176,53755,62164,69241,
%U A211032 77466,86047,96474,105249,118114,128261,141542,154371,168172
%N A211032 Number of 2 X 2 matrices having all elements in {0,1,...,n} and determinant in the open interval (-n,n).
%C A211032 For a guide to related sequences, see A210000.
%t A211032 a = 0; b = n; z1 = 40;
%t A211032 t[n_] := t[n] = Flatten[Table[w*z - x*y, {w, a, b}, {x, a, b}, {y, a, b}, {z, a, b}]]
%t A211032 c[n_, k_] := c[n, k] = Count[t[n], k]
%t A211032 c1[n_, m_] := c1[n, m] = Sum[c[n, k], {k, -n, m}]
%t A211032 Table[c1[n, n - 1] - c1[n, -n], {n, 1, z1}] (* A211032 *)
%Y A211032 Cf. A210000, A211031.
%K A211032 nonn
%O A211032 1,1
%A A211032 _Clark Kimberling_, Mar 30 2012