%I #11 Nov 25 2023 03:40:15
%S 1,3,7,7,13,13,19,19,19,19,29,29,37,37,37,37,43,43,53,53,53,53,61,61,
%T 61,61,61,61,71,71,79,79,79,79,79,79,89,89,89,89,101,101,107,107,107,
%U 107,113,113,113,113,113,113,131,131,131,131,131,131,139,139,151,151
%N a(n) = smallest number m (obviously prime) such that pi(m) = 2*pi(n).
%o (PARI) a(n) = my(k=1, nb=primepi(n)); while(primepi(k) != 2*nb, k++); k; \\ _Michel Marcus_, Nov 25 2023
%Y Cf. A000720.
%K nonn
%O 1,2
%A _Amarnath Murthy_, Aug 16 2002
%E More terms from _Jason Earls_, Aug 22 2002