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A281566
Number of 4Xn 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
1
0, 6, 815, 3374, 12133, 31300, 67834, 136056, 264286, 498750, 924374, 1694678, 3076872, 5538752, 9905630, 17619912, 31184144, 54940940, 96415390, 168598070, 293855280, 510636866, 884919690, 1529682370, 2638054884, 4539684028
OFFSET
1,2
COMMENTS
Row 4 of A281563.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) -15*a(n-2) +23*a(n-3) -27*a(n-4) +21*a(n-5) -4*a(n-6) -9*a(n-7) +15*a(n-8) -14*a(n-9) +3*a(n-10) +3*a(n-11) -3*a(n-12) +3*a(n-13) -a(n-15) for n>24
EXAMPLE
Some solutions for n=4
..0..0..1..1. .0..1..1..0. .0..1..0..0. .0..1..1..0. .0..1..1..0
..0..1..1..0. .1..1..0..0. .1..0..1..0. .0..0..1..0. .0..0..1..1
..1..0..0..0. .0..0..1..1. .1..0..1..0. .1..1..0..0. .0..1..0..0
..1..0..1..1. .1..0..1..0. .0..1..1..0. .0..1..0..1. .1..1..0..1
CROSSREFS
Cf. A281563.
Sequence in context: A341554 A365511 A321426 * A271637 A249126 A337162
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 24 2017
STATUS
approved