A250655 Number of (n+1) X (7+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.

81, 169, 345, 697, 1401, 2809, 5625, 11257, 22521, 45049, 90105, 180217, 360441, 720889, 1441785, 2883577, 5767161, 11534329, 23068665, 46137337, 92274681, 184549369, 369098745, 738197497, 1476395001, 2952790009, 5905580025

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); also a(n) = 2^(n-1)*49 + (5*2^(n-1)-1)*7 +2^(n+1).

Empirical g.f.: x*(81 - 74*x) / ((1 - x)*(1 - 2*x)). - Colin Barker, Nov 15 2018

Example

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

Crossrefs

Column 7 of A250656.

Sequence in context: A043324 A267696 A232923 * A184003 A183995 A044413

Adjacent sequences: A250652 A250653 A250654 * A250656 A250657 A250658

Keyword

nonn

Author

R. H. Hardin, Nov 26 2014

Status

approved