Achilles numbers: Difference between revisions

<tt>"0</tt> maps a function onto the individual (rank 0) items of a list or array (we use this to avoid complexities: for example if we padded our lists of prime factor powers with zeros, we could still find the gcd, but our test that the powers are greater than 1 would fail). (Actually... we could change <tt>*/ .>&1</tt> to <tt>(0 = 1 e. ])</tt> but padding would still be a bad idea here, for performance reasons. Perhaps we ought to have an option for q: to return a sparse array...)