A206662 Number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.

423, 2691, 17844, 119727, 815847, 5593611, 38594841, 267189276, 1854776850, 12896494731, 89778289281, 625461045417, 4359732229497, 30399727224177, 212022747357321, 1478983212563424, 10317870774963420, 71985922839937911

Offset

1,1

Comments

Column 2 of A206668.

Links

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

Formula

Empirical: a(n) = 14*a(n-1) -37*a(n-2) -242*a(n-3) +1172*a(n-4) +717*a(n-5) -9633*a(n-6) +5674*a(n-7) +31176*a(n-8) -35091*a(n-9) -39354*a(n-10) +60926*a(n-11) +15852*a(n-12) -33558*a(n-13) -12834*a(n-14) +15013*a(n-15) +2888*a(n-16) -2402*a(n-17) -318*a(n-18) -11*a(n-19) +49*a(n-20) for n>22.

Example

Some solutions for n=4:
..2..2..0....2..1..1....0..1..0....2..1..0....1..2..0....2..2..0....2..0..1
..0..2..2....1..1..2....1..2..1....2..1..2....0..2..0....1..2..0....2..0..1
..0..2..0....0..1..2....2..1..0....2..0..1....0..2..2....2..2..0....0..0..0
..2..2..2....1..1..1....0..2..1....1..2..0....2..2..1....2..0..0....1..1..2
..2..0..0....0..1..0....1..0..2....0..1..0....0..2..2....2..2..2....2..0..0

Crossrefs

Sequence in context: A348099 A096024 A205980 * A205831 A206408 A238174

Adjacent sequences: A206659 A206660 A206661 * A206663 A206664 A206665

Keyword

nonn

Author

R. H. Hardin, Feb 11 2012

Status

approved