A258553 Number of (n+1) X (7+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.

2008, 894, 2542, 4313, 8612, 13833, 21653, 31254, 43655, 57928, 75822, 96565, 121226, 148915, 181429, 218044, 259877, 306086, 358516, 416491, 481176, 551777, 630187, 715778, 809763, 911396, 1022618, 1142849, 1273350, 1413423, 1565057

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - 4*a(n-5) + 6*a(n-6) - 4*a(n-7) + a(n-8) for n>15.

Empirical g.f.: x*(2008 - 7138*x + 11014*x^2 - 8523*x^3 + 3036*x^4 + 3127*x^5 - 7731*x^6 + 6028*x^7 - 3207*x^8 + 2064*x^9 - 606*x^10 - 26*x^11 + 4*x^12 - 12*x^13 + 10*x^14) / ((1 - x)^5*(1 + x)*(1 + x^2)). - Colin Barker, Dec 22 2018

Example

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

Crossrefs

Column 7 of A258554.

Sequence in context: A250922 A201343 A219083 * A258560 A281987 A172735

Adjacent sequences: A258550 A258551 A258552 * A258554 A258555 A258556

Keyword

nonn

Author

R. H. Hardin, Jun 03 2015

Status

approved