A119002 - OEIS

%I #25 Jun 18 2025 06:11:56

%S 1,1,1,2,3,5,9,18,56,144,320

%N Maximal determinant of real n X n symmetric (0,1) matrices.

%C The determinant of this 8 X 8 matrix is a(8) = 56:

%C   {0, 1, 1, 1, 0, 1, 0, 0},

%C   {1, 0, 1, 1, 0, 1, 0, 0},

%C   {1, 1, 0, 1, 0, 0, 1, 1},

%C   {1, 1, 1, 0, 1, 0, 0, 1},

%C   {0, 0, 0, 1, 1, 1, 0, 1},

%C   {1, 1, 0, 0, 1, 1, 1, 0},

%C   {0, 0, 1, 0, 0, 1, 1, 1},

%C   {0, 0, 1, 1, 1, 0, 1, 0}

%C and the determinant of this 9 X 9 matrix is a(9) = 144:

%C   {1, 1, 0, 1, 1, 0, 0, 1, 1},

%C   {1, 1, 1, 1, 0, 1, 0, 0, 0},

%C   {0, 1, 1, 1, 0, 0, 1, 1, 1},

%C   {1, 1, 1, 0, 1, 0, 1, 0, 1},

%C   {1, 0, 0, 1, 0, 1, 1, 0, 1},

%C   {0, 1, 0, 0, 1, 1, 1, 1, 0},

%C   {0, 0, 1, 1, 1, 1, 0, 0, 1},

%C   {1, 0, 1, 0, 0, 1, 0, 1, 1},

%C   {1, 0, 1, 1, 1, 0, 1, 1, 0}. - _Jean-François Alcover_, Nov 18 2017

%H <a href="/index/De#determinants">Index entries for sequences related to maximal determinants</a>

%F a(n) <= A003432(n).

%Y Cf. A003432, A119003, A119004, A118998.

%K nonn,more

%O 0,4

%A _Giovanni Resta_, May 08 2006

%E a(8) and a(9) from _Jean-François Alcover_, Nov 18 2017

%E a(0)=1 prepended by _Alois P. Heinz_, Nov 18 2017

%E a(10) from _Max Alekseyev_, Jun 17 2025