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 A168089 #14 Dec 09 2018 06:41:31
%S A168089 1,1,1,1,2,2,4,16,256,65536,2147483648,2305843009213693952,
%T A168089 1329227995784915872903807060280344576,
%U A168089 110427941548649020598956093796432407239217743554726184882600387580788736
%N A168089 a(n) = 2^pentanacci(n).
%H A168089 Vincenzo Librandi, <a href="/A168089/b168089.txt">Table of n, a(n) for n = 0..16</a>
%F A168089 a(n) = 2^A001591(n).
%t A168089 2^LinearRecurrence[{1, 1, 1, 1, 1}, {0, 0, 0, 0, 1}, 15] (* _Vincenzo Librandi_, Dec 09 2018 *)
%Y A168089 Cf. A001591, A000301, A063401, A168088.
%K A168089 nonn
%O A168089 0,5
%A A168089 _Vladimir Joseph Stephan Orlovsky_, Nov 18 2009