write output of for loop in pari to file

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Hi all,

I would like to write the output of a for loop in Pari to a file named 'foo', However the output of a for loop has no numbering contrast with other output. If I look at the numbers labeling the outputs before and after the for loop and use that number in the following command

\w n foo

Then what I get in foo is 0. What happened and how can this be fixed?