This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075081 #16 Jun 14 2021 15:59:04 %S A075081 27,2187,1594323,7509466514979724803946715958257547, %T A075081 13915193059764305937984450503671774362956903094027 %N A075081 Perfect powers q (A001597) such that (q-1)/2 is prime. %C A075081 It can be shown that q must be of the form 3^e with e prime. %C A075081 The next terms are 3^541, 3^1091, 3^1367, 3^1627, 3^4177, 3^9011, 3^9551, ... %H A075081 Bo Gyu Jeong, <a href="/A075081/b075081.txt">Table of n, a(n) for n = 1..9</a> %Y A075081 Cf. A075079, A076481, A028491. %K A075081 nonn,hard %O A075081 1,1 %A A075081 _Zak Seidov_, Oct 16 2002 %E A075081 Extended by _Dean Hickerson_, Oct 16 2002