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A281557
Number of nX2 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, 0, 1, 6, 57, 310, 1508, 6854, 29487, 122326, 493459, 1947088, 7547120, 28825124, 108734941, 405846502, 1500971233, 5506856450, 20061712660, 72628513234, 261461893675, 936516327062, 3339154281263, 11856367499652, 41938909254744
OFFSET
1,4
COMMENTS
Column 2 of A281563.
LINKS
FORMULA
Empirical: a(n) = 9*a(n-1) -24*a(n-2) +9*a(n-3) +18*a(n-4) +45*a(n-5) -41*a(n-6) -36*a(n-7) -18*a(n-8) +36*a(n-9) +12*a(n-10) -8*a(n-12)
EXAMPLE
All solutions for n=4
..0..0. .0..1. .0..1. .0..1. .0..0. .0..1
..0..0. .0..0. .0..0. .1..1. .1..1. .1..1
..0..0. .0..0. .0..0. .1..1. .1..1. .1..1
..1..1. .1..0. .0..1. .1..0. .1..1. .0..1
CROSSREFS
Cf. A281563.
Sequence in context: A083696 A288680 A181430 * A227813 A221575 A001593
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 24 2017
STATUS
approved