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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.
1
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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 17 2014
STATUS
approved