A253345 - OEIS

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A253345

Number of (n+1) X (3+1) 0..1 arrays with every 2 X 2 subblock diagonal maximum minus antidiagonal maximum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.

125, 724, 4800, 30920, 199512, 1285960, 8289288, 53433608, 344449224, 2220470152, 14314275912, 92277661448, 594874191816, 3834903188104, 24722024949576, 159372675116552, 1027409972582088, 6623289504223624, 42697625485315656

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 9*a(n-1) - 8*a(n-2) - 72*a(n-3) + 96*a(n-4) + 128*a(n-5) - 128*a(n-6) - 64*a(n-7) for n>8.

Empirical g.f.: x*(125 - 401*x - 716*x^2 + 2512*x^3 - 240*x^4 - 2192*x^5 + 512*x^6 + 512*x^7) / ((1 - 2*x)*(1 - 2*x - 4*x^2)*(1 - 5*x - 12*x^2 + 16*x^3 + 8*x^4)). - Colin Barker, Dec 11 2018

EXAMPLE

Some solutions for n=4:

..1..1..1..1....1..0..0..0....1..1..1..1....0..0..0..1....0..0..1..1

..0..1..1..1....1..1..1..1....0..0..0..0....1..1..1..1....0..0..1..0

..0..1..0..0....1..0..0..1....0..0..0..0....0..1..1..1....0..0..1..1

..0..1..0..0....1..1..1..1....1..1..1..1....1..1..1..1....1..1..1..0

..1..1..1..1....0..0..1..1....0..0..1..0....1..1..1..0....0..1..1..1

CROSSREFS

Column 3 of A253350.

Sequence in context: A250944 A251288 A060093 * A016815 A253352 A204611

Adjacent sequences: A253342 A253343 A253344 * A253346 A253347 A253348

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2014

STATUS

approved