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URL: https://oeis.org/A250658

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A250658
Number of (4+1) X (n+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.
1
79, 142, 221, 316, 427, 554, 697, 856, 1031, 1222, 1429, 1652, 1891, 2146, 2417, 2704, 3007, 3326, 3661, 4012, 4379, 4762, 5161, 5576, 6007, 6454, 6917, 7396, 7891, 8402, 8929, 9472, 10031, 10606, 11197, 11804, 12427, 13066, 13721, 14392, 15079, 15782
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 8*n^2 + 39*n + 32.
Conjectures from Colin Barker, Nov 15 2018: (Start)
G.f.: x*(79 - 95*x + 32*x^2) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3.
(End)
EXAMPLE
Some solutions for n=4:
..1..1..1..1..1....0..0..0..0..0....1..1..1..0..0....1..1..1..0..0
..1..1..1..1..1....1..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..1....0..0..0..0..0
..1..1..1..1..1....0..0..0..0..0....0..0..0..0..1....0..1..1..1..1
..0..1..1..1..1....0..0..0..0..0....0..0..0..0..1....0..1..1..1..1
CROSSREFS
Row 4 of A250656.
Sequence in context: A349234 A141997 A107184 * A029703 A142082 A031890
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 26 2014
STATUS
approved