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Number of n X n 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.
0

%I #6 Apr 21 2020 12:58:16

%S 0,4,21,80,225,548,1211,2512,4989,9604,18073,33432,61035,110276,

%T 197581,351568,621945

%N Number of n X n 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

%C Diagonal of A280440.

%e Some solutions for n=4

%e ..0..0..1..0. .0..1..0..1. .0..1..0..1. .0..0..1..1. .0..0..1..0

%e ..1..1..0..1. .1..0..1..0. .1..0..1..0. .0..1..0..0. .1..0..1..0

%e ..0..0..1..0. .0..1..0..0. .0..1..0..1. .1..0..1..1. .0..1..0..1

%e ..0..1..0..1. .1..0..1..0. .0..1..1..0. .0..1..0..0. .0..1..0..1

%Y Cf. A280440.

%K nonn

%O 1,2

%A _R. H. Hardin_, Jan 03 2017