A105439 - OEIS

%I #9 Nov 12 2019 14:35:55

%S 3,5,3,5,3,17,5,3,59,5,3,11,17,5,3,29,5,3,17,41,11,41,5,3,5,3,137,11,

%T 71,5,3,5,3,17,29,11,71,5,3,5,3,5,3,11,17,5,3,137,5,3,41,11,17,5,3,41,

%U 5,3,11,227,5,3,71,11,137,5,3,41,71,41,29,59,29,17,179,11,191,5,3,5,3

%N a(n) = the smallest prime p such that p+2 and q+2 are prime; q is the n-th prime after p.

%H Harvey P. Dale, <a href="/A105439/b105439.txt">Table of n, a(n) for n = 1..1000</a>

%e a(2)=5 because 5+2 and 11+2 are primes.

%t pqr[n_]:=Module[{p=3},While[AnyTrue[{p+2,NextPrime[p,n]+2}, CompositeQ],p= NextPrime[p]];p]; Table[pqr[n],{n,90}] (* _Harvey P. Dale_, Nov 12 2019 *)

%Y Cf. A105443, A105444, A105445.

%K nonn

%O 1,1

%A _Cino Hilliard_, May 02 2005

%E Edited by _Don Reble_, Jun 11 2007