In LL test S(n) increases very fast. So it would be useless to store the first few. Imagine 2 squared then 4,16,256,65536, etc... 2^1,2^2,2^4,2^8,2^16,2^32... so it takes no time to reach 2^M1.
And theses are computed much faster than retreiving it from a disk.
Joss.
