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 A211055 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n+1. 2
 0, 1, 4, 9, 20, 23, 51, 55, 88, 79, 181, 121, 214, 222, 323, 227, 484, 299, 605, 488, 604, 457, 1102, 623, 902, 876, 1269, 769, 1754, 893, 1728, 1370, 1634, 1436, 2811, 1303, 2100, 1964, 3184, 1637, 3622, 1823, 3403, 3171, 3138 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS For a guide to related sequences, see A210000. LINKS Chai Wah Wu, Table of n, a(n) for n = 1..3000 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 + 1], {n, 1, z1}] (* A211055 *) CROSSREFS Cf. A210000, A211053. Sequence in context: A241351 A023377 A187408 * A336025 A308482 A136769 Adjacent sequences: A211052 A211053 A211054 * A211056 A211057 A211058 KEYWORD nonn AUTHOR Clark Kimberling, Mar 31 2012 STATUS approved

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Last modified February 23 08:25 EST 2024. Contains 370269 sequences. (Running on oeis4.)