A211141 - OEIS

A211141

Number of 2 X 2 matrices having all terms in {-n,...,0,...,n} and determinant n-1.

0, 33, 52, 156, 240, 492, 472, 1072, 832, 1612, 1540, 2408, 1680, 4144, 2296, 4064, 4352, 5900, 3592, 8236, 4464, 9544, 7712, 9168, 6208, 15984, 8812, 12232, 11968, 17504, 9464, 23712, 10976, 21772, 17440, 19960

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OFFSET

0,2

COMMENTS

For a guide to related sequences, see A210000.

LINKS

Chai Wah Wu, Table of n, a(n) for n = 0..3000

MATHEMATICA

a = -n; 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]

Table[c[n, n - 1], {n, 0, z1}] (* A211141 *)

CROSSREFS

Cf. A210000.

Sequence in context: A109407 A204374 A261107 * A007373 A229254 A242957

Adjacent sequences: A211138 A211139 A211140 * A211142 A211143 A211144

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 02 2012

STATUS

approved