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A255221 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 0 and no row sum 2 and no column sum 2. 1
23, 22, 31, 43, 61, 88, 127, 184, 268, 391, 571, 835, 1222, 1789, 2620, 3838, 5623, 8239, 12073, 17692, 25927, 37996, 55684, 81607, 119599, 175279, 256882, 376477, 551752, 808630, 1185103, 1736851, 2545477, 3730576, 5467423, 8012896, 11743468 (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) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) for n>5.

Empirical g.f.: x*(23 - 24*x + 10*x^2 - 20*x^3 + 7*x^4) / ((1 - x)*(1 - x - x^3)). - Colin Barker, Dec 19 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Column 1 of A255228.

Sequence in context: A023465 A004464 A255228 * A072135 A204633 A010862

Adjacent sequences:  A255218 A255219 A255220 * A255222 A255223 A255224

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 17 2015

STATUS

approved

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Last modified October 19 16:17 EDT 2019. Contains 328223 sequences. (Running on oeis4.)