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A251484 Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the minimum of its antidiagonal elements. 1
236, 3456, 50576, 740096, 10830016, 158478336, 2319053056, 33935282176, 496583453696, 7266629615616, 106334404775936, 1556017884102656, 22769598050123776, 333193211119927296, 4875699416916361216 (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) = 16*a(n-1) - 20*a(n-2).

Empirical g.f.: 4*x*(59 - 80*x) / (1 - 16*x + 20*x^2). - Colin Barker, Nov 29 2018

EXAMPLE

Some solutions for n=3:

..0..1....2..1....1..1....1..3....2..2....2..0....1..3....0..0....1..3....0..2

..3..2....2..0....2..1....2..2....3..1....1..2....1..1....0..1....1..1....1..1

..0..2....2..0....1..3....1..1....0..0....0..0....0..3....1..3....1..3....0..1

..0..1....1..1....3..3....0..0....2..2....2..0....0..3....0..0....1..1....3..2

CROSSREFS

Column 1 of A251491.

Sequence in context: A334649 A233983 A251491 * A247475 A233166 A138820

Adjacent sequences:  A251481 A251482 A251483 * A251485 A251486 A251487

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 03 2014

STATUS

approved

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Last modified December 1 16:44 EST 2021. Contains 349430 sequences. (Running on oeis4.)