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A034921 Number of different determinants of n X n persymmetric matrices with entries {-1,0,+1}. 4
3, 4, 9, 23, 67, 192, 833, 2857, 13797, 53336, 302115, 1271704 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A persymmetric (or Hankel) matrix has M[ i,j ] = M[ i-k,j+k ] for all i and j (matrix is constant along antidiagonals).
LINKS
EXAMPLE
For n = 1 and 2 the possible values for the determinant are {-1, 0, 1} and {-2, -1, 0, 1}.
MATHEMATICA
M[row_] := With[{m=Length[row]}, Table[RotateLeft[row, n][[1 ;; (m+1)/2]], {n, 0, (m-1)/2}]];
a[n_] := Det[M[#]]& /@ Tuples[{-1, 0, 1}, 2n-1] // Union // Length;
Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 1, 6}] (* Jean-François Alcover, Sep 04 2017 *)
CROSSREFS
Sequence in context: A299123 A245455 A296265 * A038222 A038629 A354545
KEYWORD
nonn,nice,more
AUTHOR
Fred Lunnon, Dec 11 1999
EXTENSIONS
More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 08 2006
a(10)-a(12) from Bert Dobbelaere, Jan 26 2019
STATUS
approved

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Last modified April 12 07:22 EDT 2024. Contains 371623 sequences. (Running on oeis4.)