A186470 Number of (n+1)X8 0..2 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors

3078, 2937, 9982, 14883, 40626, 49407, 136086, 170811, 431658, 564459, 1356918, 1931673, 4382606, 6664633, 14283484, 22714258, 46720546, 76914734, 153497652, 259317918, 505928220, 871401594, 1671620876, 2921206834, 5533505212

Offset

1,1

Comments

Column 7 of A186472

Links

R. H. Hardin, Table of n, a(n) for n = 1..82

Formula

Empirical: a(n)=2*a(n-1)+a(n-2)-4*a(n-3)+4*a(n-4)-2*a(n-5) for n>16

Example

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

Crossrefs

Sequence in context: A205623 A205358 A045083 * A322607 A284660 A234781

Adjacent sequences: A186467 A186468 A186469 * A186471 A186472 A186473

Keyword

nonn

Author

R. H. Hardin Feb 22 2011

Status

approved