Number of n X n symmetric binary matrices with each 1 adjacent to exactly 1 horizontally, vertically or diagonally neighboring 1.

A191343

Number of n X n symmetric binary matrices with each 1 adjacent to exactly 1 horizontally, vertically or diagonally neighboring 1.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =24a(4) =125a(5) =1055a(6) =11754a(7) =187498a(8) =4372206a(9) =142427556a(10) =6649078485a(11) =443418423639

External references