Triangle of coefficients of cos(x)^n in polynomial for cos(nx).

Terms

a(0) =1a(1) =1a(2) =0a(3) =2a(4) =0a(5) =-1a(6) =4a(7) =0a(8) =-3a(9) =0a(10) =8a(11) =0a(12) =-8a(13) =0a(14) =1a(15) =16a(16) =0a(17) =-20a(18) =0a(19) =5a(20) =0a(21) =32a(22) =0a(23) =-48a(24) =0a(25) =18a(26) =0a(27) =-1a(28) =64a(29) =0