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A207422 Number of nX4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 0 1 0 vertically 1
9, 81, 361, 1521, 6889, 29929, 127449, 546121, 2337841, 9979281, 42601729, 181899169, 776458225, 3314189761, 14146485721, 60382741441, 257733905625, 1100096811025, 4695589958761, 20042356043161, 85547497157721 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A207426

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 4*a(n-1) +a(n-2) +8*a(n-3) -21*a(n-4) -46*a(n-5) -6*a(n-6) +35*a(n-7) +49*a(n-8) +19*a(n-9) -16*a(n-10) -21*a(n-11) -4*a(n-13) -2*a(n-14) +a(n-15)

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A207444 A207428 A208370 * A207737 A221963 A207742

Adjacent sequences:  A207419 A207420 A207421 * A207423 A207424 A207425

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 17 2012

STATUS

approved

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Last modified May 11 11:54 EDT 2021. Contains 343791 sequences. (Running on oeis4.)