A184541 Number of (n+2) X 4 binary arrays with each 3 X 3 subblock having rows and columns in lexicographically nondecreasing order.

89, 193, 340, 537, 792, 1114, 1513, 2000, 2587, 3287, 4114, 5083, 6210, 7512, 9007, 10714, 12653, 14845, 17312, 20077, 23164, 26598, 30405, 34612, 39247, 44339, 49918, 56015, 62662, 69892, 77739, 86238, 95425, 105337, 116012, 127489, 139808, 153010

Offset

1,1

Comments

Column 2 of A184548.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = (1/24)*n^4 + (3/4)*n^3 + (383/24)*n^2 + (201/4)*n + 22.

Conjectures from Colin Barker, Apr 12 2018: (Start)

G.f.: x*(89 - 252*x + 265*x^2 - 123*x^3 + 22*x^4) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

Example

Some solutions for 6 X 4:
..0..0..0..0....0..0..0..1....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..0..1....0..0..1..1
..0..0..0..1....0..0..0..1....0..0..0..1....0..0..0..1....0..1..1..1
..0..0..0..1....0..0..0..1....0..0..1..1....0..0..0..1....0..1..1..1
..0..0..1..0....0..0..1..0....0..1..0..0....0..0..0..1....1..1..1..1
..0..1..1..0....0..0..1..1....1..1..0..0....0..0..0..1....1..1..1..1

Crossrefs

Cf. A184548.

Sequence in context: A044421 A044802 A142499 * A141953 A142625 A054694

Adjacent sequences: A184538 A184539 A184540 * A184542 A184543 A184544

Keyword

nonn

Author

R. H. Hardin, Jan 16 2011

Status

approved