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 A100690 #21 Sep 08 2022 08:45:15
%S A100690 49,374,15624,546874,537109374,15869140624,12969970703124,
%T A100690 362396240234374,274181365966796874,5401670932769775390624,
%U A100690 144354999065399169921874,2692104317247867584228515624
%N A100690 a(n) = p * 5^p - 1 where p=prime(n).
%H A100690 Harvey P. Dale, <a href="/A100690/b100690.txt">Table of n, a(n) for n = 1..224</a>
%F A100690 a(n) = A064751(prime(n)) = A064751(A000040(n)). - _Michel Marcus_, Aug 27 2015
%e A100690 a(1) = 2*5^2 - 1 = 49.
%t A100690 Do[Print[Prime[n]*5^(Prime[n]) - 1], {n, 1, 20}] (* _Stefan Steinerberger_, Feb 15 2006 *)
%t A100690 #*5^#-1&/@Prime[Range[20]] (* _Harvey P. Dale_, Jun 12 2016 *)
%o A100690 (PARI) main(m)=forprime(p=2,m,print1(p * 5^p - 1,", ")) \\ _Anders Hellström_, Aug 27 2015
%o A100690 (Magma) [NthPrime(n) * 5^(NthPrime(n)) - 1: n in [1..20]]; // _Vincenzo Librandi_, Aug 27 2015
%K A100690 nonn
%O A100690 1,1
%A A100690 _Parthasarathy Nambi_, Dec 07 2004
%E A100690 More terms from _Stefan Steinerberger_, Feb 15 2006