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A235216
Number of (n+1) X (1+1) 0..2 arrays with 2 X 2 edge jumps all no more than +1 in one of the clockwise or counterclockwise directions or both.
1
59, 427, 3037, 21693, 154811, 1105027, 7887229, 56296365, 401823467, 2868074659, 20471306509, 146116977453, 1042931528411, 7444077979171, 53133207152989, 379246121605101, 2706925263075659, 19321079274023587, 137907059867885869
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) + 9*a(n-2) - 6*a(n-3) - 2*a(n-4).
Empirical g.f.: x*(59 + 73*x - 56*x^2 - 18*x^3) / (1 - 6*x - 9*x^2 + 6*x^3 + 2*x^4). - Colin Barker, Oct 17 2018
EXAMPLE
Some solutions for n=5:
..1..1....0..0....1..1....0..1....0..0....0..0....1..0....0..0....0..0....1..2
..1..2....2..1....2..0....1..2....0..0....1..2....0..0....2..1....1..1....1..0
..1..0....2..1....2..1....0..1....0..1....1..1....1..0....0..1....0..1....0..1
..1..2....2..1....2..2....2..2....2..1....0..2....1..0....1..2....0..1....0..1
..2..2....2..1....1..2....2..1....0..0....1..1....2..1....1..1....0..1....1..2
..1..2....1..2....2..2....1..0....2..1....1..2....1..2....0..0....1..1....2..2
CROSSREFS
Column 1 of A235223.
Sequence in context: A142604 A071771 A235223 * A284754 A125034 A140024
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 05 2014
STATUS
approved