If p = (22*10^k-13)/9 is prime, then 3^4*p is a term of the sequence. This happens for k = 1, 4, 7, 12, 30, 94, 178, 196, 564, ... .

a(7) > 3*10^12.

If k is in the sequence A102953 then p = (22*10^k-13)/9 is prime. 9 divides all known terms, is it true for all terms of this sequence? - Farideh Firoozbakht, Feb 06 2014