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A230970 Number of (n+2) X (1+2) 0..3 arrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero. 1
0, 16, 64, 256, 1344, 7056, 34944, 173056, 866944, 4343056, 21706944, 108493056, 542506944, 2712743056, 13563506944, 67816493056, 339083506944, 1695422743056, 8477108506944, 42385516493056, 211927608506944, 1059638172743056 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) + 20*a(n-3) + 25*a(n-4).

Empirical g.f.: 16*x^2 / ((1 + x)*(1 - 5*x)*(1 + 5*x^2)). - Colin Barker, Sep 25 2018

EXAMPLE

Some solutions for n=2:

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

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

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

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

CROSSREFS

Column 1 of A230977.

Sequence in context: A317235 A255661 A073718 * A352738 A061449 A168091

Adjacent sequences:  A230967 A230968 A230969 * A230971 A230972 A230973

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 02 2013

STATUS

approved

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Last modified August 17 00:01 EDT 2022. Contains 356180 sequences. (Running on oeis4.)