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URL: https://oeis.org/A253500

⇱ A253500 - OEIS

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A253500
Number of (6+1) X (n+1) 0..2 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.
1
19701, 22236, 29370, 40117, 63550, 113573, 220988, 457436, 995132, 2264924, 5387708, 13382876, 34622012, 92846684, 256535228, 725629916, 2088972092, 6091114844, 17921775548, 53062222556, 157780493372, 470529165404
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) for n>9.
Empirical: a(n) = 400*3^(n-3) + 2682*2^(n-1) + 16940 for n>6.
Empirical g.f.: x*(19701 - 95970*x + 112665*x^2 - 9713*x^3 + 12502*x^4 - 2660*x^5 - 2102*x^6 - 489*x^7 - 54*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Dec 16 2018
EXAMPLE
Some solutions for n=4:
..1..2..2..2..2....0..0..0..1..0....0..1..0..0..0....1..1..2..1..2
..2..2..2..2..2....1..1..1..2..1....0..1..0..0..0....1..0..1..0..1
..0..0..0..0..0....0..0..0..1..0....1..2..1..1..1....1..0..1..0..1
..2..2..2..2..2....0..0..0..1..0....0..1..0..0..0....1..0..1..0..1
..2..2..2..2..2....0..0..0..1..0....1..2..1..1..1....1..0..1..0..1
..1..1..1..1..1....0..0..0..1..0....0..1..0..0..0....1..0..1..0..1
..1..1..1..1..1....0..0..0..2..2....0..1..0..0..2....1..0..1..0..2
CROSSREFS
Row 6 of A253495.
Sequence in context: A081866 A288885 A253493 * A253454 A237096 A252206
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 02 2015
STATUS
approved