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A234029 Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having the absolute values of all six edge and diagonal differences no larger than 1. 1
61, 307, 1543, 7783, 39331, 199003, 1007683, 5105107, 25871611, 131138323, 664800571, 3370454419, 17088658027, 86644639459, 439323545083, 2227578407827, 11294972125867, 57271642785859, 290399314134427, 1472490373513267 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) - 6*a(n-2) - 18*a(n-3) - 6*a(n-4).

Empirical g.f.: x*(61 - 120*x - 240*x^2 - 78*x^3) / (1 - 7*x + 6*x^2 + 18*x^3 + 6*x^4). - Colin Barker, Oct 12 2018

EXAMPLE

Some solutions for n=5:

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

..3..3....3..3....3..3....3..3....0..1....2..1....3..3....2..2....2..2....2..1

..2..2....3..2....4..3....3..3....1..1....1..1....3..2....2..2....3..3....1..1

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

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

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

CROSSREFS

Column 1 of A234036.

Sequence in context: A302730 A234036 A142217 * A142923 A154601 A188136

Adjacent sequences:  A234026 A234027 A234028 * A234030 A234031 A234032

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 18 2013

STATUS

approved

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Last modified July 23 12:19 EDT 2021. Contains 346259 sequences. (Running on oeis4.)