A186480 Number of (n+1)X8 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors

20079, 14492, 82632, 101305, 433513, 418177, 1849873, 1894849, 7687009, 8602033, 31645329, 39574001, 131802797, 181420169, 553069145, 820669641, 2331052105, 3678141757, 9868524241, 16371829777, 41936161201, 72480530737, 178779125389

Offset

1,1

Comments

Column 7 of A186482

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=2*a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-4)-3*a(n-5) for n>18

Example

Some solutions for 3X8
..0..0..0..0..1..0..0..0....2..0..1..0..1..0..2..0....1..0..2..0..0..0..3..3
..3..0..0..0..0..1..0..0....0..2..0..1..0..1..0..2....0..1..0..2..0..0..0..3
..2..3..0..0..0..0..1..0....3..0..2..0..1..0..1..0....3..0..1..0..2..0..0..0

Crossrefs

Sequence in context: A251986 A251880 A186565 * A204864 A353034 A348346

Adjacent sequences: A186477 A186478 A186479 * A186481 A186482 A186483

Keyword

nonn

Author

R. H. Hardin Feb 22 2011

Status

approved