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A263053 Number of (n+1) X (1+1) 0..1 arrays with each row and column not divisible by 3, read as a binary number with top and left being the most significant bits. 1
2, 2, 10, 10, 42, 42, 170, 170, 682, 682, 2730, 2730, 10922, 10922, 43690, 43690, 174762, 174762, 699050, 699050, 2796202, 2796202, 11184810, 11184810, 44739242, 44739242, 178956970, 178956970, 715827882, 715827882, 2863311530, 2863311530 (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) + 4*a(n-2) - 4*a(n-3).

Conjectures from Colin Barker, Jan 01 2019: (Start)

G.f.: 2*x / ((1 - x)*(1 - 2*x)*(1 + 2*x)).

a(n) = 2^n - 2/3 - (-2)^n/3.

(End)

EXAMPLE

All solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 1 of A263060.

Sequence in context: A216708 A032005 A147801 * A066965 A066966 A132443

Adjacent sequences:  A263050 A263051 A263052 * A263054 A263055 A263056

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 08 2015

STATUS

approved

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Last modified April 3 18:20 EDT 2020. Contains 333197 sequences. (Running on oeis4.)