Primes p such that both numbers p^
A007953(p) and p^
A007954(p) end with p.
a(4) > prime(10^8)=2038074743.
Number 2*10^k-1 is a term as soon as k is a multiple of 10 and belongs to
A002957. In particular, a(4) <= 2*10^3020 - 1. -
Max Alekseyev, Jun 07 2018
