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A251130 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. 1
40, 133, 369, 919, 2129, 4699, 10033, 20947, 43077, 87703, 177389, 357271, 717625, 1439011, 2882553, 5770507, 11547389, 23102239, 46213141, 92436271, 184883985, 369781003, 739576769, 1479170179, 2958359029, 5916738919, 11833501053 (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) = 5*a(n-1) - 8*a(n-2) + 2*a(n-3) + 7*a(n-4) - 7*a(n-5) + 2*a(n-6).

Conjectures from Colin Barker, Nov 26 2018: (Start)

G.f.: x*(40 - 67*x + 24*x^2 + 58*x^3 - 60*x^4 + 17*x^5) / ((1 - x)^4*(1 + x)*(1 - 2*x)).

a(n) = (-957 + (-1)^n + 529*2^(1+n) - 540*n - 126*n^2 - 12*n^3) / 12.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 1 of A251137.

Sequence in context: A300536 A260536 A251137 * A231077 A044372 A044753

Adjacent sequences:  A251127 A251128 A251129 * A251131 A251132 A251133

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified October 21 12:47 EDT 2021. Contains 348155 sequences. (Running on oeis4.)