The On-Line Encyclopedia of Integer Sequences (OEIS)

A227381 revision #4

A227381

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

2, 7, 54, 1104, 61127, 8988949, 3657501287

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OFFSET

1,1

COMMENTS

Diagonal of A227385

LINKS

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

EXAMPLE

Some solutions for n=4

..0..0..1..0....0..0..0..0....0..1..0..0....0..0..1..0....0..0..1..0

..1..0..0..1....0..1..0..0....1..0..0..1....0..1..0..1....1..0..0..0

..0..0..1..0....1..0..0..0....0..1..1..0....0..0..1..1....0..0..0..1

..0..0..0..1....0..0..0..0....0..0..0..0....0..0..1..1....0..1..1..0

CROSSREFS

Sequence in context: A326207 A280221 A371828 * A182055 A358944 A366456

Adjacent sequences: A227378 A227379 A227380 * A227382 A227383 A227384

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 09 2013

STATUS

approved