21933950111
domain: N
Appears in sequences
- Number of n X n symmetric binary matrices containing no more than one 1 in any 2 X 2 sub-block.at n=12A139006
- Number of n X n binary matrices, symmetric about the diagonal and under 90-degree rotation, with no more than 1 one in any 2 X 2 subblock.at n=23A141486
- Number of n X n binary matrices, symmetric about the diagonal and under 90-degree rotation, with no more than 1 one in any 2 X 2 subblock.at n=26A141486