A235956 Number of (n+1) X (2+1) 0..1 arrays with the difference of the upper and lower median value of each 2 X 2 subblock in lexicographically nondecreasing order columnwise and nonincreasing rowwise.

50, 228, 928, 3574, 13346, 48848, 176420, 631130, 2242678, 7930164, 27941848, 98196574, 344438730, 1206482520, 4221685708, 14761290914, 51584989022, 180196526268, 629274809856, 2197047322662, 7669531252530, 26769919917152

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 16*a(n-2) - 22*a(n-3) + 105*a(n-4) - 66*a(n-5) - 120*a(n-6) + 176*a(n-7) - 64*a(n-8).

Empirical g.f.: 2*x*(25 - 86*x - 48*x^2 + 449*x^3 - 316*x^4 - 480*x^5 + 704*x^6 - 256*x^7) / ((1 - x)^2*(1 - 2*x)*(1 - x - 4*x^2)*(1 - 3*x - 4*x^2 + 8*x^3)). - Colin Barker, Oct 20 2018

Example

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

Crossrefs

Column 2 of A235962.

Sequence in context: A250527 A251065 A231087 * A197971 A235567 A091883

Adjacent sequences: A235953 A235954 A235955 * A235957 A235958 A235959

Keyword

nonn

Author

R. H. Hardin, Jan 17 2014

Status

approved