Sequence S with property (making all terms distinct) that (i) a(1)=3, (ii) for n in S, a(n)=a(1)+a(2)+...+a(n-1), (iii) for n not in S, a(n)=the smallest number different from a(1), ..., a(n-1) not breaking condition (ii).

A121174

Sequence S with property (making all terms distinct) that (i) a(1)=3, (ii) for n in S, a(n)=a(1)+a(2)+...+a(n-1), (iii) for n not in S, a(n)=the smallest number different from a(1), ..., a(n-1) not breaking condition (ii).