A186477 Number of (n+1)X5 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors

1251, 2049, 4810, 16762, 25633, 67714, 101305, 286290, 456113, 1219034, 2037173, 5189546, 9017049, 22136029, 39734818, 94665157, 174517432, 405721297, 764487337, 1742099164, 3341954341, 7491958474, 14584990777, 32261305429

Offset

1,1

Comments

Column 4 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>15

Example

Some solutions for 3X5
..0..0..0..3..0....0..0..0..1..0....2..0..0..0..0....2..1..0..0..0
..2..0..0..0..3....3..0..0..0..1....2..0..0..0..0....3..0..1..0..0
..0..2..0..0..2....2..3..0..0..0....2..0..0..0..1....0..3..0..1..3

Crossrefs

Sequence in context: A254287 A252958 A288354 * A045186 A344034 A344035

Adjacent sequences: A186474 A186475 A186476 * A186478 A186479 A186480

Keyword

nonn

Author

R. H. Hardin Feb 22 2011

Status

approved