Number of n X n symmetric binary matrices containing no more than one 1 in any 2 X 2 sub-block.
A139006
Number of n X n symmetric binary matrices containing no more than one 1 in any 2 X 2 sub-block.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =9a(4) =28a(5) =137a(6) =811a(7) =6884a(8) =75303a(9) =1133287a(10) =22573092a(11) =608722751a(12) =21933950111
External references
- oeis: A139006