a(n) = 1 - n^6.

Terms

a(0) =1a(1) =0a(2) =-63a(3) =-728a(4) =-4095a(5) =-15624a(6) =-46655a(7) =-117648a(8) =-262143a(9) =-531440a(10) =-999999a(11) =-1771560a(12) =-2985983a(13) =-4826808a(14) =-7529535a(15) =-11390624a(16) =-16777215a(17) =-24137568a(18) =-34012223a(19) =-47045880a(20) =-63999999a(21) =-85766120a(22) =-113379903a(23) =-148035888a(24) =-191102975a(25) =-244140624a(26) =-308915775a(27) =-387420488a(28) =-481890303