Triangle of coefficients of characteristic polynomial of M_n, the n X n matrix M_(i,j) = min(i,j).

Terms

a(0) =1a(1) =-1a(2) =1a(3) =1a(4) =-3a(5) =1a(6) =-1a(7) =5a(8) =-6a(9) =1a(10) =1a(11) =-7a(12) =15a(13) =-10a(14) =1a(15) =-1a(16) =9a(17) =-28a(18) =35a(19) =-15a(20) =1a(21) =1a(22) =-11a(23) =45a(24) =-84a(25) =70a(26) =-21a(27) =1a(28) =-1a(29) =13