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A211054 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant n-1. 2
0, 1, 2, 6, 11, 26, 27, 66, 57, 109, 109, 182, 129, 319, 187, 332, 360, 497, 309, 714, 397, 839, 690, 842, 571, 1456, 821, 1156, 1126, 1663, 907, 2264, 1071, 2106, 1708, 1976, 1798, 3449, 1513, 2474, 2358, 3874, 1839, 4372, 2065, 3973 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

For a guide to related sequences, see A210000.

LINKS

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

EXAMPLE

A(2) counts these matrices:

1 1.....2 1

1 2.....1 1

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}]  (* A211054 *)

CROSSREFS

Cf. A210000, A211053.

Sequence in context: A160966 A052326 A079118 * A034466 A191307 A007186

Adjacent sequences:  A211051 A211052 A211053 * A211055 A211056 A211057

KEYWORD

nonn

AUTHOR

Clark Kimberling, Mar 31 2012

EXTENSIONS

Offset corrected by Chai Wah Wu, Jan 04 2017

STATUS

approved

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Last modified April 19 21:09 EDT 2019. Contains 322291 sequences. (Running on oeis4.)