Hi I am trying to develop a program to find primes with n digits abc such that acb bac bca cab and cba are also primes. (obviously trivial if aaa is prime!).
An example with n=3 is 1 p: 199 919 991 1 1 1 These primes are thin on the ground since they cannot contain any of the digits 2 4 5 6 8 or 0 and I am wondering if it would be best to construct numbers omitting those containing those prohibited digits, or test every comination of p: i. n which seems wasteful, especially since I want to find all such primes below one million. Can anyone see an efficent way to produce this? Thanks in advance, Richard ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
