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A253439 Number of (5+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally. 1
181, 180, 193, 228, 300, 444, 732, 1308, 2460, 4764, 9372, 18588, 37020, 73884, 147612, 295068, 589980, 1179804, 2359452, 4718748, 9437340, 18874524, 37748892, 75497628, 150995100, 301990044, 603979932, 1207959708, 2415919260, 4831838364 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) for n>5.
Empirical: a(n) = 9*2^(n-1) + 156 for n>3.
Empirical g.f.: x*(181 - 363*x + 15*x^2 + 9*x^3 + 2*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 12 2018
EXAMPLE
Some solutions for n=4:
..1..1..1..1..1....1..1..0..0..0....0..0..0..1..0....1..0..1..1..1
..1..1..1..1..1....1..1..0..0..0....1..0..0..1..0....1..0..1..1..1
..0..0..0..0..0....1..1..0..0..0....1..0..0..1..0....1..0..1..1..1
..1..1..1..1..1....1..1..0..0..0....1..0..0..1..0....1..0..1..1..1
..0..0..0..0..0....1..1..0..0..0....1..0..0..1..0....1..0..1..1..1
..1..1..1..1..1....1..1..0..0..1....1..0..0..1..1....1..0..1..1..1
CROSSREFS
Row 5 of A253435.
Sequence in context: A357657 A253432 A218977 * A175789 A157747 A253156
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 31 2014
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)