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%I #6 Aug 20 2020 11:46:26
%S 0,3,62,3816,758338,488491106,1019565752074,6897694015722898,
%T 151249886315100454600,10749578188598491367494716
%N Number of n X n 0..1 arrays with every element equal to 1, 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.
%C Diagonal of A301615.
%e Some solutions for n=5
%e ..0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0
%e ..0..0..0..1..1. .0..0..1..0..1. .1..1..1..1..1. .1..1..1..1..1
%e ..0..1..1..1..1. .1..1..1..0..1. .1..1..0..0..1. .0..0..1..0..0
%e ..0..0..0..0..1. .0..0..0..1..0. .1..0..0..1..1. .0..0..1..0..0
%e ..1..1..0..1..1. .1..1..0..1..0. .0..0..0..1..1. .0..0..1..0..0
%Y Cf. A301615.
%K nonn
%O 1,2
%A _R. H. Hardin_, Mar 24 2018
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