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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
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
Sequence in context: A160966 A052326 A079118 * A034466 A191307 A007186
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 June 15 16:06 EDT 2024. Contains 373407 sequences. (Running on oeis4.)