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A210284 Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant n+1. 2

%I

%S 0,0,1,11,9,42,23,81,72,126,79,273,121,268,280,416,227,624,299,761,

%T 570,690,457,1384,672,1004,982,1489,769,2108,893,1980,1500,1768,1574,

%U 3308,1303,2250,2118,3658,1637,4120,1823,3751,3527,3320

%N Number of 2 X 2 matrices with all elements in {0,1,...,n} and determinant n+1.

%C See A210000 for a guide to related sequences.

%H Chai Wah Wu, <a href="/A210284/b210284.txt">Table of n, a(n) for n = 0..3000</a>

%t a = 0; b = n; z1 = 45;

%t t[n_] := t[n] = Flatten[Table[w*z - x*y, {w, a, b}, {x, a, b}, {y, a, b}, {z, a, b}]]

%t c[n_, k_] := c[n, k] = Count[t[n], k]

%t Table[c[n, n + 1], {n, 0, z1}] (* A210284 *)

%Y Cf. A210000.

%K nonn

%O 0,4

%A _Clark Kimberling_, Mar 19 2012

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Last modified September 26 05:00 EDT 2020. Contains 337346 sequences. (Running on oeis4.)