A250738 - OEIS

%I #8 Nov 17 2018 13:10:35

%S 34,38,46,62,94,158,286,542,1054,2078,4126,8222,16414,32798,65566,

%T 131102,262174,524318,1048606,2097182,4194334,8388638,16777246,

%U 33554462,67108894,134217758,268435486,536870942,1073741854,2147483678,4294967326

%N 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.

%H R. H. Hardin, <a href="/A250738/b250738.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) - 2*a(n-2); a(n) = 2^(n+1) + 30.

%F Empirical g.f.: 2*x*(17 - 32*x) /  ((1 - x)*(1 - 2*x)). - _Colin Barker_, Nov 17 2018

%e Some solutions for n=4:

%e ..0..0..0..0..0....0..0..0..0..1....1..1..1..1..1....1..1..0..0..0

%e ..1..1..1..1..1....0..0..0..0..1....0..0..0..0..0....1..1..0..0..0

%e ..1..1..1..1..1....0..0..0..0..1....1..1..1..1..1....1..1..0..0..0

%e ..1..1..1..1..1....0..0..0..0..1....0..0..0..0..0....1..1..0..0..0

%e ..0..0..0..0..0....0..0..0..0..1....1..1..1..1..1....1..1..0..0..0

%Y Column 4 of A250742.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 27 2014