Not representable by truncated tribonacci sequence 2, 4, 7, 13, 24, 44, 81, ....

Terms

a(0) =1a(1) =3a(2) =5a(3) =8a(4) =10a(5) =12a(6) =14a(7) =16a(8) =18a(9) =21a(10) =23a(11) =25a(12) =27a(13) =29a(14) =32a(15) =34a(16) =36a(17) =38a(18) =40a(19) =42a(20) =45a(21) =47a(22) =49a(23) =52a(24) =54a(25) =56a(26) =58a(27) =60a(28) =62a(29) =65