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A269105
Number of nX4 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three no more than once.
1
216, 15540, 872460, 43964700, 2085484068, 95166487524, 4227147007836, 184069947098892, 7894012975085748, 334480929126425748, 14034341507370527532, 584107408947764887164, 24145251769444080595908
OFFSET
1,1
COMMENTS
Column 4 of A269109.
LINKS
FORMULA
Empirical: a(n) = 90*a(n-1) -2559*a(n-2) +24556*a(n-3) -94959*a(n-4) +140442*a(n-5) -69169*a(n-6) for n>7
EXAMPLE
Some solutions for n=2
..3..2..0..2. .3..1..1..0. .2..3..1..3. .3..0..0..2. .0..0..2..3
..2..0..0..1. .2..0..3..1. .2..2..3..3. .3..1..0..0. .0..0..3..1
CROSSREFS
Cf. A269109.
Sequence in context: A231319 A269197 A259831 * A352980 A223359 A046234
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 19 2016
STATUS
approved