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 A242084 #13 Sep 08 2022 08:46:08
%S A242084 8,60,2100,61740,44633820,1153594260,745759583940,18798608421180,
%T A242084 11850560210900460,185976284546943991380,4652001187058965190220,
%U A242084 72740686675902780452348340,45469899385367953379053128420
%N A242084 5^p - 4^p - 1, where p is prime.
%C A242084 For p>3 all terms are divisible by 21.
%H A242084 Vincenzo Librandi, <a href="/A242084/b242084.txt">Table of n, a(n) for n = 1..100</a>
%F A242084 a(n) = A054401(A000040(n)). - _Michel Marcus_, May 05 2014
%t A242084 Table[5^Prime[n] - 4^Prime[n] - 1, {n, 1, 60}]
%o A242084 (Magma) [5^p-4^p-1: p in PrimesUpTo(60)];
%o A242084 (PARI) a(n) = my(p = prime(n)); 5^p - 4^p - 1; \\ _Michel Marcus_, May 05 2014
%Y A242084 Cf. A204768.
%K A242084 nonn,less
%O A242084 1,1
%A A242084 _Vincenzo Librandi_, May 04 2014