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A211143
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Number of 2 X 2 matrices having all terms in {-n, ..., 0, ..., n} and determinant = n^2.
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2
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1, 20, 52, 84, 132, 156, 260, 228, 356, 372, 492, 404, 804, 508, 820, 844, 964, 716, 1396, 852, 1660, 1380, 1540, 1092, 2452, 1476, 1932, 1876, 2564, 1532, 3884, 1700, 3012, 2676, 3004, 2876, 4916, 2172, 3684, 3484, 5260
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OFFSET
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0,2
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COMMENTS
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For a guide to related sequences, see A210000.
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LINKS
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MATHEMATICA
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a = -n; b = n; z1 = 40;
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^2], {n, 0, z1}] (* A211143 *)
(1/4) Table[c[n, n^2], {n, 1, z1}] (* integers *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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