A203446 Number of (n+1) X 3 0..1 arrays with column and row pair sums b(i,j)=a(i,j)+a(i,j-1) and c(i,j)=a(i,j)+a(i-1,j) such that rows of b(i,j) and columns of c(i,j) are lexicographically nondecreasing.

16, 34, 80, 174, 376, 786, 1624, 3310, 6704, 13506, 27136, 54414, 109000, 218194, 436616, 873486, 1747264, 3494850, 6990064, 13980526, 27961496, 55923474, 111847480, 223695534, 447391696, 894784066, 1789568864, 3579138510

Offset

1,1

Comments

Column 2 of A203452.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -4*a(n-2) -2*a(n-3) +5*a(n-4) -2*a(n-5).

Empirical g.f.: 2*x*(8 - 15*x + 4*x^2 + 11*x^3 - 6*x^4) / ((1 - x)^3*(1 + x)*(1 - 2*x)). - Colin Barker, Jun 04 2018

Example

Some solutions for n=10:
..0..0..1....0..0..0....0..0..1....0..0..1....1..0..1....0..0..0....0..0..0
..0..0..1....0..0..0....0..0..1....0..0..1....0..1..0....0..0..1....0..0..0
..0..1..0....0..0..1....0..0..1....0..0..1....1..0..1....0..0..1....0..0..0
..1..0..1....0..1..0....0..0..1....0..0..1....0..1..0....0..0..1....0..0..0
..1..0..1....1..0..1....0..0..1....0..1..0....1..0..1....0..1..0....0..0..1
..1..0..1....0..1..0....0..1..0....0..1..0....0..1..0....1..0..1....0..1..1
..0..1..0....0..1..0....1..0..1....0..1..0....1..0..1....1..0..1....0..1..1
..0..1..0....1..1..0....0..1..1....0..1..0....0..1..1....0..1..0....1..1..0
..0..1..0....1..1..0....0..1..1....0..1..1....1..1..1....0..1..0....1..1..0
..0..1..0....1..1..0....1..1..1....0..1..1....1..1..1....0..1..0....1..1..0
..0..1..1....1..1..0....1..1..1....0..1..1....1..1..1....1..1..0....1..1..1

Crossrefs

Cf. A203452.

Sequence in context: A350522 A132760 A209377 * A153819 A185459 A279712

Adjacent sequences: A203443 A203444 A203445 * A203447 A203448 A203449

Keyword

nonn

Author

R. H. Hardin, Jan 02 2012

Status

approved