a(0)=0. a(n) = a(n-1) + sum of positive integers which are <= n and not part of the sequence.

Terms

a(0) =0a(1) =1a(2) =3a(3) =5a(4) =11a(5) =17a(6) =29a(7) =48a(8) =75a(9) =111a(10) =157a(11) =203a(12) =261a(13) =332a(14) =417a(15) =517a(16) =633a(17) =749a(18) =883a(19) =1036a(20) =1209a(21) =1403a(22) =1619a(23) =1858a(24) =2121a(25) =2409a(26) =2723a(27) =3064a(28) =3433a(29) =3802