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.

59, 427, 3037, 21693, 154811, 1105027, 7887229, 56296365, 401823467, 2868074659, 20471306509, 146116977453, 1042931528411, 7444077979171, 53133207152989, 379246121605101, 2706925263075659, 19321079274023587, 137907059867885869

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Adjacent sequences: A235213 A235214 A235215 * A235217 A235218 A235219

Keyword

nonn

Author

R. H. Hardin, Jan 05 2014

Status

approved