A250609 - OEIS

A250609

Number of (n+1) X (6+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)-x(i-1,j) in the j direction.

502, 1172, 2236, 3890, 6526, 10928, 18664, 32870, 59818, 112052, 214660, 417818, 821878, 1627544, 3236224, 6450734, 12876706, 25725404, 51419356, 102803618, 205568302, 411093632, 822140056, 1644228470, 3288400666, 6576740228

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4).

Empirical: a(n) = 196*2^(n-1) + 99*n^2 + 177*n + 30.

Empirical g.f.: 2*x*(251 - 669*x + 447*x^2 - 128*x^3) / ((1 - x)^3*(1 - 2*x)). - Colin Barker, Nov 15 2018

EXAMPLE

Some solutions for n=6:

..1..0..1..1..0..1..0....1..1..1..1..1..0..0....0..0..0..0..0..0..0

..1..0..1..1..0..1..1....0..0..0..0..1..0..0....1..1..1..1..1..1..1

..0..0..1..1..0..1..1....0..0..0..0..1..0..0....0..0..0..0..0..0..0

..0..0..1..1..0..1..1....0..0..0..0..1..0..0....1..1..1..1..1..1..1

..0..0..1..1..0..1..1....0..0..0..0..1..0..1....1..1..1..1..1..1..1

..0..0..1..1..0..1..1....0..0..0..0..1..0..1....0..0..0..0..0..0..0

..0..0..1..1..0..1..1....0..0..0..0..1..0..1....0..0..0..1..1..1..1

CROSSREFS

Column 6 of A250611.

Sequence in context: A320215 A233429 A121577 * A251266 A001244 A160508

Adjacent sequences: A250606 A250607 A250608 * A250610 A250611 A250612

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 26 2014

STATUS

approved