Achilles numbers: Difference between revisions

<tt>(1{__&q:)</tt> is a function which returns the non-zero powerpowers of the prime factors of a positive integer. (<tt>__&q:</tt> returns both the primes and their factors, but here we do not care about the primes themselves.)

<tt>+./</tt> returns the greatest common divisor of a list, and <tt>1=+./</tt> is true if that gcd is 1 (0 if it's false).