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A186474 Number of (n+1)X2 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors 2
256, 205, 1098, 1251, 4895, 5955, 20079, 27101, 84228, 123227, 354915, 553287, 1501107, 2465976, 6374253, 10928793, 27157017, 48218637, 116026140, 211997451, 496891083, 929460999, 2132220387, 4065922560, 9164874045, 17754363633 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 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>12

EXAMPLE

Some solutions for 3X2

..0..0....2..2....3..3....3..3....2..0....2..2....2..3....0..2....2..0....0..0

..3..0....0..0....1..0....3..3....0..2....1..0....3..0....3..0....0..2....1..0

..0..3....0..0....0..1....3..3....1..2....0..1....0..3....0..3....0..0....1..1

CROSSREFS

Sequence in context: A103949 A057066 A186482 * A093861 A248776 A223600

Adjacent sequences:  A186471 A186472 A186473 * A186475 A186476 A186477

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 22 2011

STATUS

approved

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Last modified December 22 10:43 EST 2014. Contains 252340 sequences.