Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #7 May 08 2022 23:56:54
%S 31,3552,2214457,7635071835,144396520117972,15033760617564577257,
%T 8603578492435516321649249,27081302315719663051228636805358
%N Half the number of (n+1) X (n+1) 0..2 arrays with no 2 X 2 subblock having sum 4.
%C Diagonal of A183792.
%e Some solutions for 3 X 3
%e ..0..2..2....2..2..2....0..0..0....0..1..1....2..0..0....1..0..0....0..2..1
%e ..2..2..1....2..2..2....0..0..0....0..2..1....2..2..0....2..2..0....1..2..2
%e ..1..1..1....0..1..1....1..1..1....2..2..1....0..2..2....1..0..0....1..2..0
%Y Cf. A183792.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 07 2011