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A268794
Number of nX4 0..2 arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two exactly once.
1
36, 234, 950, 4800, 23994, 117062, 561116, 2652936, 12405748, 57490444, 264428454, 1208522850, 5493284922, 24851601802, 111963916212, 502590509990, 2248738675490, 10032298715910, 44640056867750, 198161794087570
OFFSET
1,1
COMMENTS
Column 4 of A268798.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +19*a(n-2) +10*a(n-3) -122*a(n-4) -320*a(n-5) -295*a(n-6) +8*a(n-7) +176*a(n-8) +20*a(n-9) -98*a(n-10) -6*a(n-11) +43*a(n-12) -6*a(n-13) -11*a(n-14) +6*a(n-15) -a(n-16) for n>19
EXAMPLE
Some solutions for n=4
..0..1..2..1. .2..2..1..2. .0..0..0..0. .1..2..2..2. .2..2..2..2
..2..2..2..2. .2..2..2..1. .0..1..0..1. .1..2..2..2. .1..2..2..1
..1..2..1..2. .1..2..2..2. .0..0..1..0. .2..2..2..1. .2..2..2..2
..2..2..2..1. .1..2..2..1. .1..0..0..0. .2..2..2..2. .1..1..2..2
CROSSREFS
Cf. A268798.
Sequence in context: A166329 A264522 A297656 * A159921 A326347 A129149
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 13 2016
STATUS
approved