A230460 - OEIS

%I #17 Oct 20 2013 12:37:27

%S 7,13,29,43,79,101,139,163,199,271,293,373,421,443,491,577,647,673,

%T 757,821,839,929,983,1061,1181,1231,1277,1307,1361,1429,1609,1667,

%U 1759,1789,1973,1997,2083,2161,2243,2339,2411,2441,2633,2663,2707,2729,2917

%N Prime(2*prime(n)).

%C A subsequence of A031378 (subsequence of A031215) and of A106349, which are both subsequences of A007821 which is the complement of A006450 in the primes A000040.

%H M. F. Hasler, <a href="/A230460/b230460.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) ~ 2n log(n) log(2n log(n)) ~ 2n (log n)^2.

%F a(n) = A000040(A100484(n)). - _Omar E. Pol_, Oct 19 2013

%e a(3) = 29 because the third prime is 5, and 2 * 5 = 10, and then we see that the tenth prime is 29.

%e a(4) = 43 because the fourth prime is 7, and 2 * 7 = 14, and then we see that the fourteenth prime is 43.

%t Prime[2Prime[Range[50]]] (* _Alonso del Arte_, Oct 19 2013 *)

%o (PARI) A230460=n->prime(2*prime(n))

%Y Cf. A217622.

%K nonn,easy

%O 1,1

%A _M. F. Hasler_, Oct 19 2013