A186479 Number of (n+1)X7 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors

5955, 8223, 21760, 67714, 108025, 305089, 418177, 1286113, 1812049, 5368065, 8100785, 22640045, 36286649, 96020681, 161275017, 408409609, 713044957, 1742523169, 3140266657, 7453942513, 13786320241, 31954929709, 60372875257

Offset

1,1

Comments

Column 6 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>17

Example

Some solutions for 3X7
..2..0..0..0..2..0..0....3..1..0..2..0..1..0....1..1..0..2..0..2..0
..3..0..0..0..0..2..0....2..0..1..0..2..0..1....1..0..1..0..2..0..2
..0..3..0..0..0..0..2....0..2..0..1..0..2..0....0..1..0..1..0..2..3

Crossrefs

Sequence in context: A133598 A028517 A289515 * A266038 A032658 A157666

Adjacent sequences: A186476 A186477 A186478 * A186480 A186481 A186482

Keyword

nonn

Author

R. H. Hardin Feb 22 2011

Status

approved