A086899
Number of real n X n invertible symmetric (0,1) matrices.
Original entry on oeis.org
1, 4, 32, 528, 18596, 1280468, 180452552, 49970930912, 27618771417328, 30088644932329872
Offset: 1
For n = 2 the 4 matrices are 10/01, 01/10, 11/10, 01/11.
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triamat[li_List] := (*see A086900*); 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}]
A118986
Number of different values taken by the permanent of a symmetric real (0,1)-matrix of order n.
Original entry on oeis.org
1, 2, 3, 6, 14, 46, 176, 908, 5802, 44053
Offset: 0
Cf.
A006125 (number of symmetric real (0,1)-matrices of order (n-1)).
A118987
Number of different values taken by the determinant of a symmetric real (+1,-1)-matrix of order n.
Original entry on oeis.org
1, 2, 2, 3, 5, 7, 11, 19, 40, 91, 214
Offset: 0
Cf.
A006125 (number of symmetric real (+1,-1)-matrices of order (n-1)).
A373915
Determinants of symmetric real {0,1}-matrices of order 9 that only occur as positive values.
Original entry on oeis.org
89, 94, 95, 97, 98, 99, 101, 102, 105, 110, 116, 125, 144
Offset: 1
A373916
Numbers that are the determinant of real {0,1}-matrices of order 10, but not of symmetric such matrices.
Original entry on oeis.org
253, 268, 274, 294, 304
Offset: 1
Showing 1-5 of 5 results.
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