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 A152058 #13 Jun 07 2025 08:19:21
%S A152058 3,7,31,127,8191,173,131071,524287,2147483647,699053,3313,13271393,
%T A152058 2305843009213693951,209659,9361975431089,10670593,
%U A152058 618970019642690137449562111,18861569,23253381919,162259276829213363391578010288127,177722254122587407,170141183460469231731687303715884105727
%N A152058 Primes in A152057 in the order of their appearance.
%H A152058 Amiram Eldar, <a href="/A152058/b152058.txt">Table of n, a(n) for n = 1..34</a>
%t A152058 Table[If[PrimeQ[s = Total[FactorInteger[2^n - 1][[;; , 1]]]], s, Nothing], {n, 1, 50}] (* _Amiram Eldar_, Jun 07 2025 *)
%Y A152058 Cf. A046800, A152057.
%K A152058 nonn
%O A152058 1,1
%A A152058 _Roger L. Bagula_, Nov 22 2008
%E A152058 Edited by _N. J. A. Sloane_, Nov 26 2008
%E A152058 Definition revised, offset corrected and more terms added by _Amiram Eldar_, Jun 07 2025