a(0)=0; a(n) is the smallest m such that m - a(i) is not a triangular number for any i < n.

Terms

a(0) =0a(1) =2a(2) =4a(3) =9a(4) =11a(5) =13a(6) =18a(7) =20a(8) =22a(9) =27a(10) =29a(11) =31a(12) =51a(13) =53a(14) =60a(15) =62a(16) =69a(17) =71a(18) =85a(19) =94a(20) =101a(21) =103a(22) =110a(23) =112a(24) =141a(25) =143a(26) =150a(27) =152a(28) =159a(29) =161