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A206990 Number of nX4 0..1 arrays avoiding 0 0 0 horizontally and 1 1 1 vertically 1
13, 169, 840, 6510, 46878, 329952, 2371090, 16939450, 120961040, 864671390, 6178621414, 44150290200, 315500062138, 2254527357770, 16110599565656, 115124947986150, 822671737926942, 5878731842796456, 42008857944366290 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A206994

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) +17*a(n-2) +135*a(n-3) +74*a(n-4) -7*a(n-5) -1496*a(n-6) +492*a(n-7) -890*a(n-8) +4192*a(n-9) -1374*a(n-10) +1082*a(n-11) -3316*a(n-12) +622*a(n-13) +112*a(n-14) +684*a(n-15) -125*a(n-16) -42*a(n-17) -43*a(n-18) +7*a(n-19) +2*a(n-20) +a(n-21) for n>23

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A207957 A208041 A208030 * A264367 A015961 A264133

Adjacent sequences:  A206987 A206988 A206989 * A206991 A206992 A206993

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 14 2012

STATUS

approved

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Last modified August 14 03:05 EDT 2020. Contains 336477 sequences. (Running on oeis4.)