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A251021 Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. 1
110, 526, 1966, 6321, 18330, 49481, 126955, 314337, 759223, 1803024, 4233655, 9867700, 22890708, 52944048, 122232716, 281893771, 649688256, 1496798491, 3447701193, 7940432539, 18286472653, 42111425346, 96975351381, 223315141022 (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) = 7*a(n-1) - 18*a(n-2) + 17*a(n-3) + 10*a(n-4) - 39*a(n-5) + 38*a(n-6) - 17*a(n-7) + 3*a(n-8).

Empirical g.f.: x*(110 - 244*x + 264*x^2 + 157*x^3 - 571*x^4 + 557*x^5 - 255*x^6 + 46*x^7) / ((1 - x)^6*(1 - x - 3*x^2)). - Colin Barker, Nov 24 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 1 of A251028.

Sequence in context: A285984 A158539 A251028 * A251030 A156852 A250536

Adjacent sequences:  A251018 A251019 A251020 * A251022 A251023 A251024

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 29 2014

STATUS

approved

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Last modified October 2 01:30 EDT 2022. Contains 357191 sequences. (Running on oeis4.)