Not the sum of three perfect powers greater than 1.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =8a(8) =9a(9) =10a(10) =11a(11) =13a(12) =14a(13) =15a(14) =18a(15) =19a(16) =23a(17) =30a(18) =31a(19) =46a(20) =55a(21) =87a(22) =111a(23) =119a(24) =151a(25) =167a(26) =335a(27) =1391a(28) =1455a(29) =1607