A205653 Number of (n+1)X3 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.

1976, 12296, 75108, 489984, 3323532, 23019504, 162377816, 1156073240, 8289295516, 59533017872, 428906318808, 3088913281608, 22288072580932, 160654914298920, 1159724849930116, 8361789529936496, 60368998110838220

Offset

1,1

Comments

Column 2 of A205659.

Links

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

Formula

Empirical: a(n) = 60*a(n-2) +22*a(n-3) -393*a(n-4) -796*a(n-5) -3283*a(n-6) -4400*a(n-7) +12703*a(n-8) +31467*a(n-9) -4307*a(n-10) -74423*a(n-11) -49777*a(n-12) +60344*a(n-13) +59244*a(n-14) -117021*a(n-15) -209936*a(n-16) +67194*a(n-17) +403998*a(n-18) +251043*a(n-19) -196160*a(n-20) -288308*a(n-21) -24656*a(n-22) +112318*a(n-23) +44464*a(n-24) -16020*a(n-25) -9600*a(n-26) for n>31.

Example

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

Crossrefs

Sequence in context: A135845 A121995 A061998 * A206182 A205364 A210160

Adjacent sequences: A205650 A205651 A205652 * A205654 A205655 A205656

Keyword

nonn

Author

R. H. Hardin, Jan 30 2012

Status

approved