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 A342644 #9 Mar 18 2021 20:19:17
%S A342644 2,2,7,23,19,43,137,139,239,283,373,491,1019,929,2609,2699,1499,4451,
%T A342644 3191,4441,5261,3251,6373,7853,8623,9013,6359,10289,9109,6833,7703,
%U A342644 13417,19441,15329,19793,9311,16319,13109,12539,23899,26347,10111,11351,19687,27851,13627,34129,18521,27277,35537
%N A342644 Primes in A340180.
%C A342644 Terms are listed in the order in which they appear in A340180, including repetitions.
%C A342644 Repeated terms include a(1) = a(2) = 2, a(55) = a(56) = 17333, and a(233) = a(319) = 1253761. Are there any others?
%H A342644 Robert Israel, <a href="/A342644/b342644.txt">Table of n, a(n) for n = 1..5000</a>
%F A342644 a(n) = A340180(A342630(n)).
%e A342644 a(4) = A340180(A342630(4)) = A340180(14) = 23.
%p A342644 f:= proc(n) local s,k;
%p A342644 s:= numtheory:-sigma(n);
%p A342644 add(`if`(igcd(n,k)=1, s mod k, 0),k=1..n-1);
%p A342644 end proc:
%p A342644 select(isprime,map(f, [$1..1000]));
%t A342644 Select[Array[Sum[Mod[DivisorSigma[1, #], k] Floor[1/GCD[k, #]], {k, # - 1}] &, 500], PrimeQ] (* _Michael De Vlieger_, Mar 17 2021 *)
%Y A342644 Cf. A340180, A342630.
%K A342644 nonn
%O A342644 1,1
%A A342644 _J. M. Bergot_ and _Robert Israel_, Mar 17 2021