Let M_n be the n X n matrix M_(i,j) = 2^i-2^j then the characteristic polynomial of M_n = x^n-a(n)*x^(n-2).

A077122

Let M_n be the n X n matrix M_(i,j) = 2^i-2^j then the characteristic polynomial of M_n = x^n-a(n)*x^(n-2).