[Gretl-users] Creating a series

Hi, I'd like to create a series of which an observation will refer to (or will be calculated using) the previous observation of the same series. For example, I want to end up with a series like below: 0 5 10 15 20 25 30 Is it possible to create this series with a command similar to: series s = s(-1) + 5 (Of course, this series can be generated by a formula like obs * 5 but this is not what I meant.) In such a command, one observation will be calculated by a function which receives the previous observation. The command above wouldn't compile with error "The symbol 's' is undefined" because at the time of the declaration there's no variable as s. Could you recommend a solution ? Best regards, Bulent Erdemir