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A255075 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum one and no antidiagonal sum one. 1
208, 676, 2444, 8836, 31960, 115600, 418200, 1512900, 5473500, 19802500, 71645000, 259210000, 937825000, 3393062500, 12276187500, 44415562500, 160696875000, 581406250000, 2103546875000, 7610701562500, 27535773437500, 99625351562500 (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) - 25*a(n-3) + 25*a(n-4) for n>5.

Empirical g.f.: 4*x*(52 - 91*x - 234*x^2 + 454*x^3 - 130*x^4) / ((1 - 5*x + 5*x^2)*(1 - 5*x^2)). - Colin Barker, Dec 18 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Column 1 of A255082.

Sequence in context: A131686 A235273 A255082 * A304281 A234549 A234543

Adjacent sequences:  A255072 A255073 A255074 * A255076 A255077 A255078

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 14 2015

STATUS

approved

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Last modified September 27 21:12 EDT 2021. Contains 347698 sequences. (Running on oeis4.)