A250730 Number of (1+1)X(n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction

9, 22, 50, 114, 257, 579, 1302, 2927, 6578, 14782, 33216, 74637, 167709, 376840, 846753, 1902638, 4275190, 9606266, 21585085, 48501247, 108981314, 244878791, 550237650, 1236372778, 2778104416, 6242343961, 14026419561, 31517078668

Offset

1,1

Comments

Row 1 of A250729

Links

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

Formula

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

Empirical: G.f. x*( -9+5*x+7*x^2-4*x^3 ) / ( (x-1)*(x^3-x^2-2*x+1) ). - R. J. Mathar, Nov 27 2014

Example

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

Crossrefs

Sequence in context: A049730 A131895 A323221 * A251285 A197498 A287497

Adjacent sequences: A250727 A250728 A250729 * A250731 A250732 A250733

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved