A206680 Number of (n+1) X 4 0..2 arrays with every 2 X 3 or 3 X 2 subblock having an unequal number of clockwise and counterclockwise edge increases.

1404, 9792, 89022, 645144, 5747676, 41876592, 373903296, 2722587120, 24304785252, 176985022704, 1579981448832, 11505224983296, 102709417207548, 747917148492864, 6676804424256600, 48619655397737136, 434037286978243404

Offset

1,1

Comments

Column 3 of A206685.

Links

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

Formula

Empirical: a(n) = 60*a(n-2) + 332*a(n-4) - 366*a(n-6) - 3833*a(n-8) + 2454*a(n-10) + 1844*a(n-12) + 3288*a(n-14) + 9008*a(n-16) - 864*a(n-18) for n>19.

Example

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

Crossrefs

Sequence in context: A271579 A271712 A352239 * A022058 A107522 A158764

Adjacent sequences: A206677 A206678 A206679 * A206681 A206682 A206683

Keyword

nonn

Author

R. H. Hardin, Feb 11 2012

Status

approved