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 A033872 #11 Jun 18 2019 03:29:52 %S A033872 8,10,12,14,15,16,18,20,21,22,26,27,28,30,32,33,34,35,38,39,42,44,45, %T A033872 46,48,50,51,52,55,56,57,58,62,63,64,65,68,69,72,74,75,76,77,80,81,82, %U A033872 85,86,87,90,91,92,93,94,95,98,99 %N A033872 Numbers k such that A033831(k) is prime. %H A033872 Amiram Eldar, <a href="/A033872/b033872.txt">Table of n, a(n) for n = 1..10000</a> %t A033872 f[n_] := DivisorSum[n, 1&, # > 2 && n/# < #-1 &]; Select[Range[1000], PrimeQ[f[#]] &] (* _Amiram Eldar_, Jun 11 2019 *) %o A033872 (PARI) isok(n) = isprime(sumdiv(n, d, (d>=3) && (q=n/d) && (q>=1) && (q<=d-2))); \\ _Michel Marcus_, Jun 11 2019 %Y A033872 Cf. A033831. %K A033872 easy,nonn %O A033872 1,1 %A A033872 _Naohiro Nomoto_