Well, for starters, if P is your given prime number, 2*}.i.&.(p:inv)P%2
would all be “almost prime” so that suggests one approach: calculate i.&.(p:inv)P%2 then work your way through th low prime values while trimming off excessive numbers from the remaining sequence... — Raul On Monday, December 31, 2018, Bernie Eckhart <[email protected]> wrote: > 1, 3, 673, 2019 > > 4 factors is almost a prime. > > Let's denote only 4 factor numbers like 2019, i.e. every factor is a unique > integer that occurs only once, as "almost a prime" number. > > A problem is to compute efficiently all "almost a prime" numbers between 1 > and any given prime number. > > Almost certainly a waste of time unless some pattern might be discovered > that allows one to predict and compute primes faster than other methods. > > I have no idea where to begin because I am not a mathematician and because > I am very new to J. > > HAPPY 2019! > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
