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A186471 Number of (n+1)X9 0..2 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors 1
4553, 5790, 13985, 31866, 52755, 109950, 170811, 399018, 570183, 1266414, 1812423, 3993474, 6107001, 13004678, 20863681, 42650908, 70588930, 140178754, 237788174, 462275652, 798678366, 1528016844, 2676404634, 5059638908, 8953777234 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 8 of A186472

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..78

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>17

EXAMPLE

Some solutions for 3X9

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

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

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

CROSSREFS

Sequence in context: A031607 A193311 A020432 * A210305 A102748 A032751

Adjacent sequences:  A186468 A186469 A186470 * A186472 A186473 A186474

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 22 2011

STATUS

approved

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Last modified September 24 23:43 EDT 2022. Contains 356951 sequences. (Running on oeis4.)