a(n) is the smallest integer such that the sum of any three ordered terms a(k), k <= n, is unique.

Terms

a(0) =0a(1) =1a(2) =4a(3) =13a(4) =32a(5) =71a(6) =124a(7) =218a(8) =375a(9) =572a(10) =744a(11) =1208a(12) =1556a(13) =2441a(14) =3097a(15) =4047a(16) =5297a(17) =6703a(18) =7838a(19) =10986a(20) =12331a(21) =15464a(22) =19143a(23) =24545a(24) =28973a(25) =34405a(26) =37768a(27) =45863a(28) =50876a(29) =61371