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A262333
Number of (n+3) X (1+3) 0..1 arrays with each row and column divisible by 9, read as a binary number with top and left being the most significant bits.
1
2, 4, 8, 15, 29, 57, 114, 228, 456, 911, 1821, 3641, 7282, 14564, 29128, 58255, 116509, 233017, 466034, 932068, 1864136, 3728271, 7456541, 14913081, 29826162, 59652324, 119304648, 238609295, 477218589, 954437177, 1908874354, 3817748708
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) - a(n-3) + 3*a(n-4) - 2*a(n-5).
Empirical g.f.: x*(2 - 2*x + x^3 - 2*x^4) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x + x^2)). - Colin Barker, Dec 31 2018
EXAMPLE
Some solutions for n=4:
..0..0..0..0....1..0..0..1....0..0..0..0....1..0..0..1....0..0..0..0
..0..0..0..0....1..0..0..1....1..0..0..1....1..0..0..1....1..0..0..1
..0..0..0..0....1..0..0..1....1..0..0..1....1..0..0..1....0..0..0..0
..0..0..0..0....0..0..0..0....1..0..0..1....1..0..0..1....0..0..0..0
..0..0..0..0....1..0..0..1....1..0..0..1....1..0..0..1....1..0..0..1
..0..0..0..0....0..0..0..0....1..0..0..1....1..0..0..1....0..0..0..0
..0..0..0..0....1..0..0..1....1..0..0..1....0..0..0..0....0..0..0..0
CROSSREFS
Column 1 of A262338.
Sequence in context: A275544 A000078 A176503 * A293335 A344687 A301480
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 18 2015
STATUS
approved