%I #8 Feb 06 2023 11:56:02
%S 282,1434,4182,9762,19110,34602,56982,89766,134298,194262,271074,
%T 371478,494346,647358,833226,1057542,1321482,1636314,1999926,2425794,
%U 2913678,3472242,4104942,4828626
%N Number of idempotent 4X4 0..n matrices of rank 2.
%e Some solutions for n=3
%e ..0..0..0..0....1..0..0..0....0..0..0..0....0..0..0..0....1..0..0..0
%e ..1..1..0..0....0..1..1..0....1..1..0..0....1..1..0..0....0..1..0..0
%e ..2..1..0..1....0..0..0..0....0..0..1..0....1..1..0..1....2..2..0..0
%e ..1..0..0..1....0..3..3..0....0..0..1..0....0..0..0..1....0..3..0..0
%Y Row 4 of A224114.
%K nonn,more
%O 1,1
%A _R. H. Hardin_, Apr 09 2013