|
%I #6 Apr 21 2020 13:03:11
%S 0,0,68,3374,50510,347316,1818257,8300608,33449458,124061416,432930120
%N Number of n X n 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
%C Diagonal of A281563.
%e Some solutions for n=4
%e ..0..0..0..1. .0..1..0..0. .0..1..1..0. .0..1..1..0. .0..0..0..1
%e ..0..1..0..0. .1..0..1..1. .0..1..1..0. .1..0..1..0. .0..1..0..1
%e ..0..1..1..1. .0..0..1..0. .0..0..0..0. .0..1..1..0. .0..0..0..1
%e ..0..1..0..0. .1..1..0..0. .1..0..1..0. .1..0..1..1. .0..1..0..1
%Y Cf. A281563.
%K nonn
%O 1,3
%A _R. H. Hardin_, Jan 24 2017
| 