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

%I A211054 #10 Jan 11 2017 01:32:29
%S A211054 0,1,2,6,11,26,27,66,57,109,109,182,129,319,187,332,360,497,309,714,
%T A211054 397,839,690,842,571,1456,821,1156,1126,1663,907,2264,1071,2106,1708,
%U A211054 1976,1798,3449,1513,2474,2358,3874,1839,4372,2065,3973
%N A211054 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n-1.
%C A211054 For a guide to related sequences, see A210000.
%H A211054 Chai Wah Wu, <a href="/A211054/b211054.txt">Table of n, a(n) for n = 0..3000</a>
%e A211054 A(2) counts these matrices:
%e A211054 1 1.....2 1
%e A211054 1 2.....1 1
%t A211054 a = 1; b = n; z1 = 45;
%t A211054 t[n_] := t[n] = Flatten[Table[w*z - x*y, {w, a, b}, {x, a, b}, {y, a, b}, {z, a, b}]]
%t A211054 c[n_, k_] := c[n, k] = Count[t[n], k]
%t A211054 Table[c[n, n - 1], {n, 1, z1}]  (* A211054 *)
%Y A211054 Cf. A210000, A211053.
%K A211054 nonn
%O A211054 0,3
%A A211054 _Clark Kimberling_, Mar 31 2012
%E A211054 Offset corrected by _Chai Wah Wu_, Jan 04 2017