a(n) is smallest number which is uniquely a(j) + a(k), j < k.

Terms

a(0) =3a(1) =4a(2) =7a(3) =10a(4) =11a(5) =13a(6) =15a(7) =16a(8) =21a(9) =22a(10) =27a(11) =30a(12) =35a(13) =36a(14) =41a(15) =44a(16) =50a(17) =53a(18) =55a(19) =61a(20) =69a(21) =70a(22) =75a(23) =78a(24) =84a(25) =87a(26) =92a(27) =93a(28) =98a(29) =101