A250741 Number of (n+1) X (7+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nonincreasing x(i,j)-x(i-1,j) in the j direction.

258, 262, 270, 286, 318, 382, 510, 766, 1278, 2302, 4350, 8446, 16638, 33022, 65790, 131326, 262398, 524542, 1048830, 2097406, 4194558, 8388862, 16777470, 33554686, 67109118, 134217982, 268435710, 536871166, 1073742078, 2147483902, 4294967550

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2); a(n) = 2^(n+1) + 254.

Empirical g.f.: 2*x*(129 - 256*x) / ((1 - x)*(1 - 2*x)). - Colin Barker, Nov 17 2018

Example

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

Crossrefs

Column 7 of A250742.

Sequence in context: A308675 A121237 A161683 * A031514 A173981 A339538

Adjacent sequences: A250738 A250739 A250740 * A250742 A250743 A250744

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved