A235541 Number of (n+1) X (1+1) 0..1 arrays with the sum of each 2 X 2 subblock two median terms lexicographically nondecreasing rowwise and columnwise.

16, 48, 141, 378, 988, 2482, 6109, 14712, 34896, 81612, 188725, 432046, 980620, 2208798, 4941909, 10990620, 24311440, 53516200, 117285181, 256007874, 556755036, 1206716778, 2607303661, 5617260448, 12069653488, 25869224292

Offset

1,1

Comments

Column 1 of A235548.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 4*a(n-1) - 14*a(n-3) + 5*a(n-4) + 18*a(n-5) - 4*a(n-6) - 8*a(n-7).

Empirical g.f.: x*(16 - 16*x - 51*x^2 + 38*x^3 + 68*x^4 - 24*x^5 - 32*x^6) / ((1 - x)*(1 + x)^3*(1 - 2*x)^3). - Colin Barker, Mar 19 2018

Example

Some solutions for n=5:
..0..0....1..1....0..0....1..0....0..0....0..0....0..1....0..1....1..0....0..1
..0..1....0..0....0..1....1..0....1..0....1..0....0..0....1..0....0..1....0..0
..0..0....1..1....1..0....0..1....0..0....0..0....0..1....1..1....0..1....1..0
..1..0....0..0....1..0....1..0....0..1....0..1....1..1....0..1....1..1....1..0
..0..0....1..1....1..1....1..1....0..1....0..0....1..0....1..1....1..1....0..1
..0..1....0..1....1..0....1..1....1..1....1..0....1..1....1..0....1..0....1..1

Crossrefs

Cf. A235548.

Sequence in context: A211590 A211584 A211598 * A109098 A223395 A202329

Adjacent sequences: A235538 A235539 A235540 * A235542 A235543 A235544

Keyword

nonn

Author

R. H. Hardin, Jan 12 2014

Status

approved