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%I #6 Jun 15 2020 15:10:39
%S 0,2,9,58,306,1371,5451,20316,73826,268227,988143,3710046,14186486,
%T 55056941,215998713,853659146,3389857782,13500951049,53867577061
%N 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.
%C Diagonal of A300350.
%e Some solutions for n=5
%e ..0..0..1..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..0..1
%e ..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..1..0..1
%e ..1..0..1..0..1. .0..1..0..1..1. .0..1..0..1..0. .0..0..1..0..1
%e ..0..1..0..1..0. .0..1..0..0..0. .0..1..0..1..0. .1..1..0..1..0
%e ..0..1..0..1..0. .0..1..1..1..1. .0..1..0..1..0. .0..0..1..0..0
%Y Cf. A300350.
%K nonn
%O 1,2
%A _R. H. Hardin_, Mar 03 2018