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A252726 Number of (7+2) X (n+2) 0..3 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order. 1
257, 220, 224, 257, 288, 324, 373, 452, 512, 617, 768, 900, 1093, 1412, 1664, 2057, 2688, 3204, 3973, 5252, 6272, 7817, 10368, 12420, 15493, 20612, 24704, 30857, 41088, 49284, 61573, 82052, 98432, 123017, 163968, 196740, 245893, 327812, 393344 (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) = -a(n-1) + 3*a(n-3) + 3*a(n-4) - 2*a(n-6) - 2*a(n-7) for n>9.

Empirical g.f.: x*(257 + 477*x + 444*x^2 - 290*x^3 - 886*x^4 - 720*x^5 - 232*x^6 + 144*x^7 + 16*x^8) / ((1 - x)*(1 + x)*(1 + x + x^2)*(1 - 2*x^3)). - Colin Barker, Dec 06 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

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

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

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

CROSSREFS

Row 7 of A252719.

Sequence in context: A273775 A182912 A276233 * A260679 A043676 A296901

Adjacent sequences:  A252723 A252724 A252725 * A252727 A252728 A252729

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 20 2014

STATUS

approved

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Last modified May 20 20:15 EDT 2022. Contains 353876 sequences. (Running on oeis4.)