with(LinearAlgebra):
J:=Matrix([[lambda,1,0,0,0],
[0,lambda,1,0,0],
[0,0,lambda,1,0],
[0,0,0,lambda,1],
[0,0,0,0,lambda]]);
J.J;
J.J.J;
J.J.J.J;
J.J.J.J.J;