A227264 Number of n X n 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(n+1) binary array having a sum of three or less, with rows and columns of the latter in lexicographically nondecreasing order

2, 8, 49, 513, 10906, 498772, 48265519, 9879827545, 4332146485870

Offset

1,1

Comments

Diagonal of A227269

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for n=4
..1..1..1..1....1..1..1..1....1..1..1..1....1..1..1..1....1..1..1..1
..1..0..0..1....1..1..1..1....0..1..1..1....1..1..1..1....1..0..1..1
..1..1..0..1....1..1..1..0....0..1..1..1....0..1..1..1....1..0..1..1
..1..1..1..1....1..0..0..1....0..0..0..0....0..0..0..1....1..0..0..1

Crossrefs

Sequence in context: A332237 A136226 A046165 * A373865 A114619 A027047

Adjacent sequences: A227261 A227262 A227263 * A227265 A227266 A227267

Keyword

nonn

Author

R. H. Hardin Jul 04 2013

Status

approved