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A233106 Number of n X 1 0..5 arrays with no element x(i,j) adjacent to value 5-x(i,j) horizontally or vertically, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order. 5
1, 2, 6, 23, 99, 452, 2136, 10313, 50469, 249062, 1235466, 6147803, 30650439, 152986472, 764135196, 3818284493, 19084248009, 95399716682, 476934013326, 2384476356383, 11921800651179, 59607259863692, 298031069141856 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A233113.

LINKS

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

FORMULA

Empirical: a(n) = 9*a(n-1) - 23*a(n-2) + 15*a(n-3).

Conjectures from Colin Barker, Feb 19 2018: (Start)

G.f.: x*(1 - 7*x + 11*x^2) / ((1 - x)*(1 - 3*x)*(1 - 5*x)).

a(n) = (75 + 10*3^n + 3*5^n) / 120.

(End)

EXAMPLE

Some solutions for n=7:

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

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

..2....2....0....1....5....1....5....2....1....1....5....5....1....0....1....2

..1....4....1....5....1....5....2....0....1....5....1....5....2....4....2....5

..5....0....1....1....1....4....0....3....5....5....1....1....1....2....1....5

..1....2....2....0....2....5....3....5....1....2....1....0....5....4....3....2

..5....2....0....1....5....4....1....2....0....5....5....0....2....2....3....5

CROSSREFS

Sequence in context: A242586 A196018 A009449 * A133656 A078487 A193038

Adjacent sequences:  A233103 A233104 A233105 * A233107 A233108 A233109

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 04 2013

STATUS

approved

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Last modified September 24 05:29 EDT 2021. Contains 347623 sequences. (Running on oeis4.)