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 A211063 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant >=3n. 2
 0, 0, 0, 0, 8, 38, 122, 284, 589, 1080, 1848, 2933, 4515, 6577, 9366, 12888, 17444, 22928, 29864, 37986, 48057, 59656, 73413, 89307, 108002, 129068, 153386, 180636, 212111, 246683, 286126, 329135, 378047, 431242, 490425, 555118 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS For a guide to related sequences, see A210000. LINKS Chai Wah Wu, Table of n, a(n) for n = 0..2000 MATHEMATICA a = 1; b = n; z1 = 35; 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] s[n_, m_] := s[n, m] = Sum[c[n, k], {k, 1, m}] Table[s[n, n^2]-s[n, 3n-1], {n, 1, z1}] (* A211063 *) CROSSREFS Cf. A210000. Sequence in context: A319960 A163832 A139798 * A065762 A034009 A038732 Adjacent sequences:  A211060 A211061 A211062 * A211064 A211065 A211066 KEYWORD nonn AUTHOR Clark Kimberling, Mar 31 2012 EXTENSIONS Offset corrected by Chai Wah Wu, Jan 10 2017 STATUS approved

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Last modified December 14 17:32 EST 2019. Contains 329979 sequences. (Running on oeis4.)