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A210291 Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant >n. 2
0, 0, 6, 40, 125, 323, 647, 1235, 2074, 3337, 5057, 7477, 10436, 14490, 19436, 25591, 33015, 42259, 52849, 65833, 80528, 97909, 117905, 141163, 166651, 196474, 229796, 267289, 308712, 355766, 406488, 464094, 526402, 595477, 670963 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See A210000 for a guide to related sequences.

LINKS

Chai Wah Wu, Table of n, a(n) for n = 0..1000

MATHEMATICA

a = 0; 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]

c1[n_, m_] := c1[n, m] = Sum[c[n, k], {k, 0, m}]

Table[c1[n, n^2] - c1[n, n], {n, 0, z1}]  (* A210291 *)

CROSSREFS

Cf. A210000.

Sequence in context: A002595 A263956 A229638 * A089207 A318169 A027777

Adjacent sequences:  A210288 A210289 A210290 * A210292 A210293 A210294

KEYWORD

nonn

AUTHOR

Clark Kimberling, Mar 20 2012

STATUS

approved

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Last modified February 18 12:34 EST 2020. Contains 332018 sequences. (Running on oeis4.)