Next term is uniquely the sum of 3 earlier terms.

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =9a(5) =10a(6) =11a(7) =12a(8) =28a(9) =29a(10) =30a(11) =53a(12) =56a(13) =57a(14) =80a(15) =82a(16) =104a(17) =105a(18) =107a(19) =129a(20) =130a(21) =132a(22) =154a(23) =155a(24) =157a(25) =179a(26) =180a(27) =182a(28) =204a(29) =205