A180996 Number of n X n binary matrices with rows and columns each in strictly increasing order as binary numbers and no 1 neighboring another 1.

2, 2, 3, 7, 26, 145, 1269, 16666, 336209, 10197321, 469338906, 32492055785, 3394528588557, 533338846061070, 126158953592584561, 44869991848754725313, 24002894812644474337158, 19303006356138543308410109

Offset

1,1

Comments

Diagonal of A180997

Links

R. H. Hardin, Table of n, a(n) for n=1..24

Example

All solutions for 4X4
..0..0..0..0....0..0..0..0....0..0..0..1....0..0..0..1....0..0..0..1
..0..0..0..1....0..0..0..1....0..0..1..0....0..0..1..0....0..0..1..0
..0..0..1..0....0..0..1..0....0..1..0..0....0..1..0..0....0..1..0..0
..0..1..0..0....0..1..0..1....1..0..0..0....1..0..1..0....1..0..0..1
...
..0..0..0..1....0..0..0..1
..0..0..1..0....0..0..1..0
..0..1..0..1....0..1..0..1
..1..0..0..0....1..0..1..0

Crossrefs

Sequence in context: A038507 A185387 A077001 * A307503 A087522 A092970

Adjacent sequences: A180993 A180994 A180995 * A180997 A180998 A180999

Keyword

nonn

Author

R. H. Hardin, Sep 30 2010

Status

approved