A059786 - OEIS

%I #24 May 03 2019 17:12:53

%S 5,7,11,17,23,29,37,41,47,59,67,79,83,89,97,107,127,127,137,149,149,

%T 163,167,179,197,211,211,223,223,227,257,263,277,281,307,307,317,331,

%U 337,347,359,367,383,389,397,401,431,449,457,461,467,479,487,503,521

%N Smallest prime after 2*(n-th prime).

%H Andrew Howroyd, <a href="/A059786/b059786.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A117928(n,1) for n>1. - _Reinhard Zumkeller_, Apr 03 2006

%e n=17, 18, p(17)=59, p(18)=61, after 118 and 122 the next prime is 127, so a(17)=a(18)=127.

%p with(numtheory): [seq(nextprime(2*ithprime(k)),k=1..256)];

%t NextPrime/@(2*Prime[Range[60]]) (* _Harvey P. Dale_, May 03 2019 *)

%o (PARI) a(n) = nextprime(2*prime(n)+1); \\ _Michel Marcus_, Sep 21 2017

%Y Cf. A055496, A006992.

%K nonn

%O 1,1

%A _Labos Elemer_, Feb 22 2001