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A213990 T(n,k)=Number of n X n 0..k matrices whose square is also a 0..k matrix.

%I A213990 #10 Jul 22 2025 23:06:14
%S A213990 2,2,11,2,24,172,3,36,1003,6327,3,72,2546,120133,474286,3,92,8168,
%T A213990 604639,35799856,67147431,3,126,14030,3510112,421195466,24651985100,
%U A213990 17080038508,3,148,28328,9131098,5018010431,801373175814
%N A213990 T(n,k)=Number of n X n 0..k matrices whose square is also a 0..k matrix.
%e A213990 Some solutions for n=3 k=4
%e A213990 ..1..0..2....0..4..1....2..0..0....2..2..0....0..4..4....0..3..3....0..3..2
%e A213990 ..0..2..0....0..0..0....0..0..0....0..0..2....1..0..0....1..0..0....0..1..0
%e A213990 ..0..0..1....0..1..0....0..0..2....0..0..0....0..0..0....0..0..0....0..0..0
%e A213990 Table starts
%e A213990 ...........2...........2............2..........3.......3.....3...3.3
%e A213990 ..........11..........24...........36.........72......92...126.148
%e A213990 .........172........1003.........2546.......8168...14030.28328
%e A213990 ........6327......120133.......604639....3510112.9131098
%e A213990 ......474286....35799856....421195466.5018010431
%e A213990 ....67147431.24651985100.801373175814
%e A213990 .17080038508
%Y A213990 Column 1 is A121231
%K A213990 nonn,tabl,more
%O A213990 1,1
%A A213990 _R. H. Hardin_, Jun 30 2012