A119004
Number of n X n real symmetric (0,1)-matrices having maximal determinant (=A119002(n)).
Original entry on oeis.org
1, 1, 1, 18, 160, 900, 2520, 36960, 393120, 15573600
Offset: 1
A086900
Number of real n X n symmetric (0,1) matrices with positive determinant.
Original entry on oeis.org
1, 1, 5, 338, 14186, 526876, 52658844, 28076946520, 18518751047608, 13637385623943256
Offset: 1
For n = 2 the only example is the identity matrix.
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triamat[li_List] := Block[{len=Sqrt[8Length[li]+1]/2-1/2}, If[IntegerQ[len], Part[li, # ]& /@ Table[If[j>i, j(j-1)/2+i, i(i-1)/2+j], {i, len}, {j, len}], li]]; Table[it=triamat/@ IntegerDigits[Range[0, -1+2^(n(n+1)/2)], 2, n(n+1)/2]; Count[it, (q_)?MatrixQ/;(Det[q]>0)], {n, 5}]
A118998
Minimal determinant of real n X n symmetric (0,1) matrices.
Original entry on oeis.org
0, -1, -2, -3, -5, -9, -32, -56, -128, -320
Offset: 1
A119003
Maximal determinant of real n X n symmetric (+1,-1) matrices.
Original entry on oeis.org
1, 0, 4, 16, 48, 160, 576, 4096, 14336, 65536
Offset: 1
A119006
Number of n X n real symmetric (0,1)-matrices having minimal determinant (=A118998(n)).
Original entry on oeis.org
1, 3, 3, 8, 60, 1620, 840, 23520, 756000, 30996000
Offset: 1
A119008
Number of n X n real symmetric (0,1)-matrices with determinant = 1.
Original entry on oeis.org
1, 1, 4, 268, 9456, 301306, 24846368, 8946957244, 4175660906560, 2421067614753916
Offset: 1
A351984
a(n) is the number of symmetric anti-Hadamard matrices of order n whose sum of the inverse squares of their singular values is maximal.
Original entry on oeis.org
1, 2, 6, 24, 120, 840, 5040
Offset: 1
Showing 1-7 of 7 results.
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