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 A211053 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n. 4
 0, 2, 7, 16, 23, 50, 45, 93, 99, 150, 117, 283, 167, 308, 336, 443, 289, 654, 369, 803, 658, 762, 543, 1392, 779, 1092, 1086, 1563, 879, 2160, 1011, 2038, 1652, 1888, 1758, 3323, 1445, 2386, 2302, 3730, 1795, 4220, 1989, 3889, 3737 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For a guide to related sequences, see A210000. LINKS Chai Wah Wu, Table of n, a(n) for n = 1..3000 EXAMPLE a(2) counts these 2 matrices: 2 1.....2 2 2 2.....1 2 MATHEMATICA a = 1; b = n; z1 = 45; 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], {n, 1, z1}] (* A211053 *) CROSSREFS Cf. A210000. Sequence in context: A225323 A167236 A041573 * A041341 A296857 A229595 Adjacent sequences: A211050 A211051 A211052 * A211054 A211055 A211056 KEYWORD nonn AUTHOR Clark Kimberling, Mar 31 2012 STATUS approved

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Last modified April 18 22:18 EDT 2024. Contains 371782 sequences. (Running on oeis4.)