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A227442 T(n,k) = Number of n X k 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X (k+1) binary array having two adjacent 1's and two adjacent 0's. 5
2, 4, 4, 8, 16, 8, 16, 62, 62, 16, 32, 240, 457, 240, 32, 64, 932, 3346, 3346, 932, 64, 128, 3620, 24568, 46126, 24568, 3620, 128, 256, 14056, 180575, 636996, 636996, 180575, 14056, 256, 512, 54576, 1327102, 8802600, 16517429, 8802600, 1327102, 54576, 512 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Table starts

...2......4........8..........16...........32............64...........128

...4.....16.......62.........240..........932..........3620.........14056

...8.....62......457........3346........24568........180575.......1327102

..16....240.....3346.......46126.......636996.......8802600.....121623396

..32....932....24568......636996.....16517429.....428106288...11089818502

..64...3620...180575.....8802600....428106288...20779660903.1007348570226

.128..14056..1327102...121623396..11089818502.1007348570226

.256..54576..9752326..1680297950.287216470434

.512.211912.71665377.23214121178

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..84

FORMULA

Empirical for column k:

k=1: a(n) = 2*a(n-1).

k=2: a(n) = 4*a(n-1) -2*a(n-2) +6*a(n-3).

k=3: [order 9].

EXAMPLE

Some solutions for n=4, k=4

..1..0..1..1....0..0..0..0....1..0..1..1....1..0..0..0....0..1..1..0

..1..0..1..0....1..1..0..1....0..1..0..0....0..0..0..0....0..0..0..1

..1..0..0..1....1..1..1..0....1..0..0..1....0..0..0..0....0..0..1..1

..1..1..1..1....1..1..1..0....1..0..0..0....0..1..0..0....0..1..0..0

CROSSREFS

Column 1 is A000079.

Sequence in context: A297102 A283415 A283857 * A282316 A228986 A188910

Adjacent sequences:  A227439 A227440 A227441 * A227443 A227444 A227445

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Jul 11 2013

STATUS

approved

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Last modified December 1 01:37 EST 2021. Contains 349426 sequences. (Running on oeis4.)