A121174 - OEIS

A121174

Sequence S with property (making all terms distinct) that (i) a(1)=3, (ii) for n is 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).

3, 4, 7, 14, 6, 34, 68, 9, 145, 11, 301, 13, 615, 1230, 16, 2476, 18, 4970, 20, 9960, 22, 19942, 24, 39908, 26, 79842, 28, 159712, 30, 319454, 32, 638940, 35, 1277915, 2555830, 37, 5111697, 39, 10223433, 41, 20446907, 43, 40893857, 45