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A253498 Number of (4+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
3639, 4720, 6931, 10477, 18526, 37469, 82676, 194708, 483572, 1255700, 3383156, 9387668, 26645492, 76907540, 224670836, 661915028, 1961556212, 5836296980, 17412153716, 52042992788, 155742047732, 466452288020, 1397809159796 (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) = 400*3^(n-3) + 738*2^(n-1) + 3044 for n>6.
Empirical g.f.: x*(3639 - 17114*x + 18640*x^2 - 1023*x^3 + 3585*x^4 - 26*x^5 - 1214*x^6 - 345*x^7 - 54*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Dec 16 2018
EXAMPLE
Some solutions for n=4:
..2..2..1..1..1....0..2..2..2..2....0..2..2..2..1....0..2..2..2..2
..1..1..0..0..0....1..1..1..1..1....1..1..1..1..0....2..2..2..2..2
..1..1..0..0..0....1..1..1..1..1....1..1..1..1..0....0..0..0..0..0
..2..2..1..1..1....0..0..0..0..0....1..1..1..1..0....2..2..2..2..2
..2..2..1..1..2....0..0..0..0..1....2..2..2..2..1....0..0..0..0..1
CROSSREFS
Row 4 of A253495.
Sequence in context: A206898 A207288 A239992 * A253491 A253452 A253464
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 02 2015
STATUS
approved

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Last modified March 1 12:07 EST 2024. Contains 370433 sequences. (Running on oeis4.)