A235673 Number of (n+1) X (2+1) 0..1 arrays with the difference between each 2 X 2 subblock maximum and minimum lexicographically nondecreasing columnwise and nonincreasing rowwise.

58, 380, 2456, 15790, 101398, 650928, 4178316, 26820102, 172154058, 1105028596, 7092994476, 45528746034, 292241404878, 1875848682364, 12040758823136, 77287616186486, 496096276240318, 3184358988382152, 20439867526684676

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 9*a(n-2) - 9*a(n-3) + 10*a(n-4) + 3*a(n-5) - 2*a(n-6).

Empirical g.f.: 2*x*(29 - 42*x - 31*x^2 + 42*x^3 + 11*x^4 - 8*x^5) / ((1 - x)*(1 - x - x^2)*(1 - 6*x - 3*x^2 + 2*x^3)). - Colin Barker, Oct 19 2018

Example

Some solutions for n=5:
..0..0..0....1..1..0....0..1..0....1..1..1....1..0..1....0..0..1....1..1..0
..1..0..1....1..0..0....0..1..1....1..0..0....0..0..1....1..0..1....0..1..1
..0..1..1....1..0..1....0..0..1....1..0..1....0..0..0....0..1..1....1..0..0
..1..0..0....0..1..0....1..1..1....1..1..1....0..0..1....0..0..0....1..1..0
..0..0..1....1..0..1....1..0..1....1..0..1....0..0..0....0..0..1....0..0..1
..1..1..1....0..1..1....1..1..1....1..0..1....0..0..0....0..0..1....1..1..0

Crossrefs

Column 2 of A235679.

Sequence in context: A141779 A250927 A250920 * A235730 A235443 A235511

Adjacent sequences: A235670 A235671 A235672 * A235674 A235675 A235676

Keyword

nonn

Author

R. H. Hardin, Jan 13 2014

Status

approved