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 A057901 #26 Sep 08 2022 08:45:02
%S A057901 9,27,243,2187,177147,1594323,129140163,1162261467,94143178827,
%T A057901 68630377364883,617673396283947,450283905890997363,
%U A057901 36472996377170786403,328256967394537077627,26588814358957503287787
%N A057901 a(n) = 3^prime(n).
%H A057901 Vincenzo Librandi, <a href="/A057901/b057901.txt">Table of n, a(n) for n = 1..100</a>
%F A057901 a(n) = 3^A000040(n).
%F A057901 Sum_{n>=1} 1/a(n) = A132800. - _Amiram Eldar_, Aug 11 2020
%e A057901 a(4) = 3^7 = 2187.
%t A057901 3^Prime@Range@30 (* _Vladimir Joseph Stephan Orlovsky_, Apr 11 2011 *)
%o A057901 (Magma) [3^p: p in PrimesUpTo(30)]; // _Vincenzo Librandi_, Jun 03 2014
%Y A057901 Cf. A034785, A053810, A057902, A132800.
%Y A057901 Subsequence of A000244 (powers of 3).
%K A057901 nonn
%O A057901 1,1
%A A057901 _Henry Bottomley_, Sep 29 2000