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A263907
Number of (2n+2) X (2+2) 0..1 arrays with each row and column modulo 3 equal to 1, read as a binary number with top and left being the most significant bits.
1
16, 528, 14112, 359200, 9024816, 225934128, 5650549312, 141279105600, 3532085249616, 88302884507728, 2207577385564512, 55189471549212000, 1379737047100994416, 34493427986119721328, 862335712313157059712
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 33*a(n-1) - 207*a(n-2) + 175*a(n-3).
Conjectures from Colin Barker, Jan 03 2019: (Start)
G.f.: 16*x / ((1 - x)*(1 - 7*x)*(1 - 25*x)).
a(n) = (3 - 4*7^(1+n) + 25^(1+n)) / 27.
(End)
EXAMPLE
Some solutions for n=2:
..1..1..0..1....0..1..1..1....1..0..1..0....1..1..0..1....0..0..0..1
..0..1..1..1....1..1..0..1....1..0..1..0....0..1..0..0....0..1..1..1
..1..0..1..0....1..0..1..0....0..1..0..0....1..1..0..1....0..1..0..0
..1..1..0..1....0..0..0..1....1..0..1..0....0..1..1..1....1..0..1..0
..1..1..0..1....0..0..0..1....0..1..0..0....0..0..0..1....1..0..1..0
..0..1..1..1....1..1..0..1....0..0..0..1....0..1..0..0....1..1..0..1
CROSSREFS
Column 2 of A263913 (nonzero terms).
Sequence in context: A041480 A227402 A371722 * A222099 A362520 A254126
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 29 2015
STATUS
approved