### reading, computing, writing

OK, I just installed Sage for the first time and now I would like to figure out how to read and write a file as well as run 'functions' like primepi (count of prime numbers).

Axxxxxx is a sequence in the OEIS at oeis.org.

The data file has two columns "n, A104272(n)" with n > 3*10^6:

1 2
2 11
3 17
4 29
5 41
... ...

After reading the data I need it take the difference of the A182873(n) = A104272(n+1) - A104272(n), find primepi(A104272(n+1)) and primepi(A104272(n)) and the difference of those two A190874(n) = primepi(A104272(n+1)) - primepi(A104272(n)). After that I would like to write the data back to a file.

I have been looking at the tutorial, but I have not found the section on reading data or anything like it.