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A269076 Number of 2 X n binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. 1
4, 11, 27, 76, 185, 489, 1204, 3059, 7539, 18748, 46001, 112977, 275620, 671387, 1629003, 3944428, 9524969, 22955577, 55208404, 132545027, 317673891, 760222300, 1816668257, 4335499425, 10333941316, 24603369515, 58513434747, 139020574348 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 5*a(n-2) - 6*a(n-3) - 9*a(n-4).
Empirical g.f.: x*(4 + 3*x - 15*x^2 - 9*x^3) / (1 - x - 3*x^2)^2. - Colin Barker, Jan 18 2019
EXAMPLE
Some solutions for n=4:
..1..1..0..1. .0..0..1..0. .1..0..0..0. .1..0..0..0. .0..0..0..0
..0..0..0..1. .0..0..0..1. .0..0..0..0. .0..0..1..1. .1..0..1..0
CROSSREFS
Row 2 of A269075.
Sequence in context: A176759 A266009 A096124 * A282641 A031127 A239031
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 19 2016
STATUS
approved

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Last modified March 1 13:16 EST 2024. Contains 370433 sequences. (Running on oeis4.)