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A258918 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum equal to the antidiagonal sum or central row sum equal to the central column sum. 1
200, 576, 1680, 5184, 15840, 46656, 138240, 419904, 1270080, 3779136, 11275200, 34012224, 102409920, 306110016, 916090560, 2754990144, 8278407360, 24794911296, 74304112320, 223154201664, 669946334400, 2008387814976 (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) - 6*a(n-2) + 18*a(n-3).

Empirical g.f.: 8*x*(25 - 3*x + 144*x^2) / ((1 - 3*x)*(1 + 6*x^2)). - Colin Barker, Dec 23 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Column 1 of A258921.

Sequence in context: A117412 A109632 A258921 * A129641 A202966 A218846

Adjacent sequences:  A258915 A258916 A258917 * A258919 A258920 A258921

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 14 2015

STATUS

approved

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Last modified November 29 10:41 EST 2021. Contains 349416 sequences. (Running on oeis4.)