A205660 Number of 3X(n+1) 0..3 arrays with every 2 X 2 subblock having the same number of clockwise edge increases as its horizontal neighbors and no 2 X 2 subblock having the same number of counterclockwise edge increases as its vertical neighbors.

2120, 12296, 95008, 839872, 7919128, 76028256, 732727336, 7068433736, 68201154272, 658081945168, 6349980210408, 61272516345744, 591233822472776, 5704963557044152, 55048626862970856, 531178036521593464

Offset

1,1

Comments

Row 2 of A205659.

Links

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

Formula

Empirical: a(n) = 12*a(n-1) -7*a(n-2) -173*a(n-3) +94*a(n-4) +1137*a(n-5) +190*a(n-6) -3906*a(n-7) -4350*a(n-8) +5407*a(n-9) +16999*a(n-10) +5544*a(n-11) -28150*a(n-12) -28396*a(n-13) +18360*a(n-14) +34596*a(n-15) -399*a(n-16) -17679*a(n-17) -2832*a(n-18) +5324*a(n-19) +1556*a(n-20) -636*a(n-21) -240*a(n-22) for n>26.

Example

Some solutions for n=4:
..2..0..0..1..0....1..3..0..1..1....1..2..0..1..3....3..1..3..3..3
..3..2..1..3..1....0..1..2..0..2....1..3..2..0..2....1..1..1..1..1
..2..2..3..3..1....3..3..2..1..3....2..2..2..2..2....1..1..1..1..1

Crossrefs

Sequence in context: A031770 A031680 A031544 * A205949 A205460 A263510

Adjacent sequences: A205657 A205658 A205659 * A205661 A205662 A205663

Keyword

nonn

Author

R. H. Hardin, Jan 30 2012

Status

approved