A250738 Number of (n+1) X (4+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.

34, 38, 46, 62, 94, 158, 286, 542, 1054, 2078, 4126, 8222, 16414, 32798, 65566, 131102, 262174, 524318, 1048606, 2097182, 4194334, 8388638, 16777246, 33554462, 67108894, 134217758, 268435486, 536870942, 1073741854, 2147483678, 4294967326

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) + 30.

Empirical g.f.: 2*x*(17 - 32*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..1....1..1..1..1..1....1..1..0..0..0
..1..1..1..1..1....0..0..0..0..1....0..0..0..0..0....1..1..0..0..0
..1..1..1..1..1....0..0..0..0..1....1..1..1..1..1....1..1..0..0..0
..1..1..1..1..1....0..0..0..0..1....0..0..0..0..0....1..1..0..0..0
..0..0..0..0..0....0..0..0..0..1....1..1..1..1..1....1..1..0..0..0

Crossrefs

Column 4 of A250742.

Sequence in context: A218006 A345510 A300155 * A281239 A295750 A141699

Adjacent sequences: A250735 A250736 A250737 * A250739 A250740 A250741

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved