A059786 Smallest prime after 2*(n-th prime).

5, 7, 11, 17, 23, 29, 37, 41, 47, 59, 67, 79, 83, 89, 97, 107, 127, 127, 137, 149, 149, 163, 167, 179, 197, 211, 211, 223, 223, 227, 257, 263, 277, 281, 307, 307, 317, 331, 337, 347, 359, 367, 383, 389, 397, 401, 431, 449, 457, 461, 467, 479, 487, 503, 521

Offset: 1

Author

Labos Elemer, Feb 22 2001

Keywords

• nonn

Examples

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

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A055496, A006992.

Programs

Maple

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

Mathematica

NextPrime/@(2*Prime[Range[60]]) (* Harvey P. Dale, May 03 2019 *)

PARI

a(n) = nextprime(2*prime(n)+1); \\ Michel Marcus, Sep 21 2017

Formula

a(n) = A117928(n,1) for n>1. - Reinhard Zumkeller, Apr 03 2006