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A252222 Number of (n+2) X (2+2) 0..2 arrays with every 3 X 3 subblock row and column sum 2 3 or 4 and every diagonal and antidiagonal sum not 2 3 or 4. 1
368, 1028, 3066, 7724, 22256, 70284, 219824, 675264, 2072804, 6383492, 19670396, 60581792, 186548780, 574478144, 1769185920, 5448417444, 16778894996, 51672129164, 159129275664, 490053971084, 1509168106704, 4647627251072 (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) = 3*a(n-1) - a(n-2) + 3*a(n-3) + 3*a(n-4) - a(n-5) - a(n-6) for n>9.

Empirical g.f.: 2*x*(184 - 38*x + 175*x^2 - 775*x^3 - 1019*x^4 - 337*x^5 + 127*x^6 + 115*x^7 + 3*x^8) / ((1 - x + 2*x^2 - x^3)*(1 - 2*x - 3*x^2 - x^3)). - Colin Barker, Dec 02 2018

EXAMPLE

Some solutions for n=4:

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

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

..0..2..0..2....0..2..0..2....2..0..2..0....2..0..2..0....2..0..2..0

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

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

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

CROSSREFS

Column 2 of A252228.

Sequence in context: A336981 A307010 A098823 * A173055 A318938 A240006

Adjacent sequences:  A252219 A252220 A252221 * A252223 A252224 A252225

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 15 2014

STATUS

approved

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Last modified September 25 14:37 EDT 2021. Contains 347654 sequences. (Running on oeis4.)