A227258 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 two or less, with rows and columns of the latter in lexicographically nondecreasing order

2, 9, 98, 2201, 112349, 13855163, 4307345460

Offset

1,1

Comments

Diagonal of A227263

Links

Table of n, a(n) for n=1..7.

Example

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

Crossrefs

Sequence in context: A317275 A013057 A237929 * A027686 A360696 A357825

Adjacent sequences: A227255 A227256 A227257 * A227259 A227260 A227261

Keyword

nonn

Author

R. H. Hardin Jul 04 2013

Status

approved