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A231045 Number of n X 4 0..3 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4 and at least one element with value (x(i,j)-1) mod 4, no adjacent elements equal, and upper left element zero. 1
0, 32, 128, 2080, 18688, 209440, 2150784, 22847008, 239510016, 2523778080, 26540458624, 279321664544, 2938791541504, 30923196075552, 325371816285056, 3423602175951392, 36023310011880448, 379040068394055712 (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) = 8*a(n-1) + 33*a(n-2) - 68*a(n-3).

Empirical g.f.: 32*x^2*(1 - 4*x) / (1 - 8*x - 33*x^2 + 68*x^3). - Colin Barker, Sep 25 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 4 of A231049.

Sequence in context: A033323 A091905 A100626 * A031447 A153074 A035503

Adjacent sequences:  A231042 A231043 A231044 * A231046 A231047 A231048

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 03 2013

STATUS

approved

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Last modified October 23 03:21 EDT 2019. Contains 328335 sequences. (Running on oeis4.)