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 A123488 #11 Jun 26 2019 00:40:22 %S A123488 3,7,31,127,12207031,8191,131071,524287, %T A123488 1484520425576434196455942238665054573307722183, %U A123488 10333327940128053377465393536117755205850522803739374960650929 %N A123488 Smallest prime of the form (q^p-1)/(q-1), where p = prime(n) and q is also prime (q = A123487(n)). %C A123488 Corresponding smallest primes q are listed in A123487. %C A123488 a(n) coincides with A084732(n) when A066180(n) is prime or 0. %F A123488 a(n) = (A123487(n)^prime(n) - 1) / (A123487(n) - 1). %Y A123488 Cf. A123487, A066180, A084732. %K A123488 nonn %O A123488 1,1 %A A123488 _Alexander Adamchuk_, Sep 30 2006