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Number of n X 2 arrays containing 2 copies of 0..n-1 with no element 1 greater than its west or north neighbor modulo n and the upper left element equal to 0.
0

%I #9 Apr 15 2024 17:55:59

%S 1,0,2,35,1007,54819,4318217,458508379,62976460150,10860600443527,

%T 2297243685069637,584799993257765106

%N Number of n X 2 arrays containing 2 copies of 0..n-1 with no element 1 greater than its west or north neighbor modulo n and the upper left element equal to 0.

%C Column 2 of A266318.

%e Some solutions for n=4:

%e ..0..2....0..3....0..2....0..2....0..3....0..2....0..3....0..3....0..3....0..2

%e ..0..2....3..2....2..1....2..1....0..3....3..1....2..1....0..2....3..1....0..2

%e ..3..1....2..1....1..3....1..0....2..1....2..1....2..1....3..2....2..1....3..1

%e ..3..1....1..0....0..3....3..3....2..1....0..3....0..3....1..1....2..0....1..3

%Y Cf. A266318.

%K nonn,more

%O 1,3

%A _R. H. Hardin_, Dec 27 2015