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A253452 Number of (n+1) X (4+1) 0..2 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally and vertically. 1
3639, 8554, 11147, 15730, 26831, 52912, 114717, 266911, 656997, 1694263, 4540077, 12545551, 35498037, 102227623, 298160637, 877448191, 2598287877, 7726760983, 23044088397, 68859886831, 206034914517, 617015262343, 1848866835357 (list; graph; refs; listen; history; text; internal format)
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) = 529*3^(n-3) + 1039*2^(n-1) + 5372 for n>6.
Empirical g.f.: x*(3639 - 13280*x - 148*x^2 + 21108*x^3 + 3744*x^4 - 1926*x^5 - 1994*x^6 - 345*x^7 - 54*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Dec 13 2018
EXAMPLE
Some solutions for n=4:
..1..1..2..1..0....0..0..0..1..1....0..1..2..1..1....1..1..0..2..0
..2..1..2..1..0....2..1..0..0..0....2..2..2..1..1....2..1..0..2..0
..2..1..2..1..0....2..1..0..0..0....1..1..1..0..0....2..1..0..2..0
..2..1..2..1..0....2..1..0..0..0....1..1..1..0..0....2..1..0..2..0
..0..0..2..2..2....1..0..0..1..2....0..0..0..0..1....2..1..0..2..0
CROSSREFS
Column 4 of A253456.
Sequence in context: A239992 A253498 A253491 * A253464 A015294 A186870
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 01 2015
STATUS
approved

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Last modified February 20 17:05 EST 2024. Contains 370213 sequences. (Running on oeis4.)