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 A364807 #101 Sep 07 2023 19:56:01
%S A364807 2,3,5,6,8,9,18,19,21,26,29,34,48,50,56,63,69,79,84,87,95,97,99,101,
%T A364807 110,111,132,134,139,149,151,157,160,163,164,168,171,187,201,204,209,
%U A364807 220,222,226,227,231,244,250,256,258,268,276,282,290,292,294,296,306
%N A364807 Numbers k such that abs(k - Sum_{m=2..k} pi(prime(k)/m)) is a prime number, where pi(k) is number of primes <= k.
%C A364807 Inspired by Ramanujan primes A104272.
%C A364807 Primes in common with A104272 are 2, 29, 97, 101, 149, 151, 227, ...; of those, the first twin prime pair is (149, 151).
%C A364807 pi(a(n)) ~ a(n)/log_2(n), where pi(a(n)) is number of primes <= a(n).
%e A364807 k=6 is a term: abs(6 - Sum_{m=2..6} pi(prime(k)/m)) = abs(6 - 3 - 2 - 2 - 1 - 1) = abs(-3) = 3, which is prime.
%t A364807 Select[Range[320], PrimeQ[Abs[# - Sum[PrimePi[Prime[#]/m], {m, 2, #}]]] &] (* _Amiram Eldar_, Aug 08 2023 *)
%Y A364807 Cf. A000720, A104272.
%K A364807 nonn,easy
%O A364807 0,1
%A A364807 _Saish S. Kambali_, Aug 08 2023