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A183467
Number of n X 2 binary arrays with every element equal to either the sum mod 2 of its vertical neighbors or the sum mod 2 of its horizontal neighbors.
1
2, 6, 12, 28, 68, 156, 368, 872, 2048, 4832, 11408, 26896, 63456, 149728, 353216, 833344, 1966144, 4638656, 10944000, 25820288, 60917760, 143723520, 339087616, 800010496, 1887468032, 4453111296, 10506243072, 24787422208, 58481067008
OFFSET
1,1
COMMENTS
Column 2 of A183474.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 4*a(n-3) - 4*a(n-4) - 4*a(n-6).
Empirical g.f.: 2*x*(1 + x - 2*x^3 - 2*x^4 - 2*x^5) / ((1 - 2*x^3)*(1 - 2*x - 2*x^3)). - Colin Barker, Mar 29 2018
EXAMPLE
Some solutions for 4 X 2:
..0..0....1..1....0..0....0..0....1..1....1..1....1..1....1..1....1..1....0..0
..0..0....1..0....1..1....0..0....0..0....0..0....1..1....1..1....0..0....1..1
..0..0....0..1....1..1....1..1....1..0....0..0....0..0....1..1....0..0....1..1
..0..0....1..1....0..0....1..1....1..0....1..1....0..0....0..0....0..0....1..1
CROSSREFS
Cf. A183474.
Sequence in context: A191394 A237500 A330455 * A057582 A094779 A093387
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 05 2011
STATUS
approved