%I #6 Mar 12 2019 04:51:07
%S 1,9,481,148817,243782721
%N Number of nilpotent n X n matrices with elements {-1, 0, 1}.
%H S. E. Thornton, <a href="http://www.bohemianmatrices.com/cpdb/unstructured/unstructured_n1_0_1">Properties of the Bohemian family of n x n matrices with population {-1, 0, 1}</a>, Characteristic Polynomial Database.
%Y Number of characteristic polynomials is in A272658.
%Y Number of distinct eigenvalues is in A271570.
%K nonn,more,hard
%O 1,2
%A _Steven E. Thornton_, Mar 11 2019