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A300343
Number of n X n 0..1 arrays with every element equal to 1 or 2 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
0
0, 2, 9, 58, 306, 1371, 5451, 20316, 73826, 268227, 988143, 3710046, 14186486, 55056941, 215998713, 853659146, 3389857782, 13500951049, 53867577061
OFFSET
1,2
COMMENTS
Diagonal of A300350.
EXAMPLE
Some solutions for n=5
..0..0..1..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..0..1
..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..1..0..1
..1..0..1..0..1. .0..1..0..1..1. .0..1..0..1..0. .0..0..1..0..1
..0..1..0..1..0. .0..1..0..0..0. .0..1..0..1..0. .1..1..0..1..0
..0..1..0..1..0. .0..1..1..1..1. .0..1..0..1..0. .0..0..1..0..0
CROSSREFS
Cf. A300350.
Sequence in context: A111545 A070075 A124405 * A141787 A047852 A240881
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 03 2018
STATUS
approved