%I #16 Jun 14 2021 15:59:04
%S 27,2187,1594323,7509466514979724803946715958257547,
%T 13915193059764305937984450503671774362956903094027
%N Perfect powers q (A001597) such that (q-1)/2 is prime.
%C It can be shown that q must be of the form 3^e with e prime.
%C The next terms are 3^541, 3^1091, 3^1367, 3^1627, 3^4177, 3^9011, 3^9551, ...
%H Bo Gyu Jeong, <a href="/A075081/b075081.txt">Table of n, a(n) for n = 1..9</a>
%Y Cf. A075079, A076481, A028491.
%K nonn,hard
%O 1,1
%A _Zak Seidov_, Oct 16 2002
%E Extended by _Dean Hickerson_, Oct 16 2002