A250787 Number of (5+1) X (n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.

144, 396, 990, 2426, 5688, 12950, 28692, 62274, 132890, 279864, 583196, 1205236, 2474328, 5053216, 10277030, 20831790, 42114880, 84962234, 171112172, 344149014, 691415474, 1387878796, 2783929300, 5581085336, 11183577088, 22401796180

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 12*a(n-2) + 5*a(n-3) + 13*a(n-4) - 16*a(n-5) + 2*a(n-6) + 5*a(n-7) - 2*a(n-8).

Empirical g.f.: 2*x*(72 - 234*x + 171*x^2 + 259*x^3 - 420*x^4 + 70*x^5 + 148*x^6 - 64*x^7) / ((1 - x)^4*(1 + x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 20 2018

Example

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

Crossrefs

Row 5 of A250783.

Sequence in context: A211469 A248551 A178972 * A188246 A258382 A151820

Adjacent sequences: A250784 A250785 A250786 * A250788 A250789 A250790

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved