Find number property and write RPL program (HP-49G,G+, HP 50g)

[Thomas Ritschel]

(09-24-2014 04:04 PM)Gerson W. Barbosa Wrote:  Only 22% of the first thousand prime numbers are in the list, and this percentage drops to about 8% for the first million numbers, so I was amazed at finding one 11-digit such prime in a universe of only 12 numbers.
Too many hints by now :-)

That were indeed too many hints!
Your numbers are Sophie-Germain primes, e.g. prime numbers p for which 2p+1 is also prime.

Unfortunately I don't have my 50g with me right now. So I would leave it to someone else to present a RPL solution...