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A183359 One quarter the number of nX7 1..4 arrays with no two neighbors of any element equal to each other 1
972, 36864, 34992, 63504, 137088, 331776, 829440, 1806336, 3852288, 8294400, 18137088, 40144896, 88897536, 196448256, 433465344, 955551744, 2106667008, 4645785600, 10246588416, 22600912896, 49849804800, 109947949056 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A183362

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..58

FORMULA

Empirical: a(n)=2*a(n-1)+a(n-3)-2*a(n-4)+4*a(n-5)+a(n-6)-a(n-9) for n>14

EXAMPLE

Some solutions for 5X7 with a(1,1)=1

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

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

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

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

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

CROSSREFS

Sequence in context: A206089 A217162 A203375 * A203030 A209045 A209017

Adjacent sequences:  A183356 A183357 A183358 * A183360 A183361 A183362

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 04 2011

STATUS

approved

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Last modified January 19 03:54 EST 2020. Contains 331031 sequences. (Running on oeis4.)