login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Table of n, a(n) for n=1..12.

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-Fran├žois Alcover, Sep 04 2017 *)

CROSSREFS

Cf. A034917, A034918, A034919, A034920.

Sequence in context: A299123 A245455 A296265 * A038222 A038629 A247087

Adjacent sequences:  A034918 A034919 A034920 * A034922 A034923 A034924

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 17 19:10 EDT 2019. Contains 324198 sequences. (Running on oeis4.)