A250577 Number of (n+1) X (2+1) 0..1 arrays with nondecreasing max(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.

24, 60, 142, 329, 758, 1743, 4009, 9223, 21227, 48864, 112503, 259042, 596486, 1373534, 3162900, 7283395, 16771972, 38622017, 88937775, 204803649, 471616777, 1086027506, 2500877597, 5758959852, 13261592356, 30538471600, 70323248330

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - 5*a(n-3) + 8*a(n-4) - 3*a(n-5).

Empirical g.f.: x*(24 - 36*x - 26*x^2 + 61*x^3 - 24*x^4) / ((1 - x)^3*(1 - x - 3*x^2)). - Colin Barker, Nov 15 2018

Example

Some solutions for n=6:
..0..0..1....1..1..1....1..1..1....0..0..1....0..0..1....0..0..1....0..1..1
..1..0..1....0..1..1....1..1..1....1..0..1....1..1..1....0..0..1....0..1..1
..0..1..0....1..1..1....0..1..1....0..1..1....0..1..1....0..1..1....1..1..1
..1..0..1....0..1..1....1..1..1....1..0..1....0..1..1....1..0..1....0..1..1
..0..1..1....0..1..1....0..1..1....0..1..1....1..0..1....0..1..1....0..1..1
..0..1..1....0..1..1....0..1..1....0..1..1....0..1..1....1..0..1....1..0..1
..0..1..1....0..1..1....0..1..1....1..0..1....1..1..1....0..1..0....0..1..0

Crossrefs

Column 2 of A250583.

Sequence in context: A182464 A211571 A240524 * A242844 A185445 A321840

Adjacent sequences: A250574 A250575 A250576 * A250578 A250579 A250580

Keyword

nonn

Author

R. H. Hardin, Nov 25 2014

Status

approved