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 A340742 #11 Jan 19 2021 04:48:20 %S A340742 2,2,2,7,2,7,5,7,19,13,47,31,31,17,53,41,127,79,61,113,103,229,149,73, %T A340742 257,383,173,613,263,293,439,541,787,883,1039,647,643,1129,1151,1181, %U A340742 769,1153,1303,1559,2153,2221,2393,3881,1427,1429,4211,3691,1291,3919,1549,2371,4691,4909,2251,2713,2143,4957,3863,4073,4337 %N A340742 Primes in A340740, in the order in which they occur. %C A340742 Terms occurring more than once include 2, 7, 31, and 4073. Are there any others? %H A340742 Robert Israel, <a href="/A340742/b340742.txt">Table of n, a(n) for n = 1..5000</a> %F A340742 a(n) = A340740(A340741(n)). %e A340742 a(3) = A340740(9) = 2. %p A340742 f:= proc(n) local k; %p A340742 add(`if`(igcd(k, n)=1, n mod k, 0), k=1..floor(n/2)) %p A340742 end proc: %p A340742 select(isprime, map(f, [$1..1000])); %Y A340742 Cf. A340736, A340740, A340741. %K A340742 nonn %O A340742 1,1 %A A340742 _J. M. Bergot_ and _Robert Israel_, Jan 18 2021