A152050 - OEIS

%I #4 Mar 12 2015 19:15:48

%S 3,5,3,5,3,5,3,5,11,5,3,5,3,5,5,11,5,3,11,5,3,5,11,3,5,3,5,3,17,3,5,

%T 11,11,17,5,5,3,5,5,11,11,5,3,29,11,11,3,5,3,5,11,29,5,5,5,11,5,3,11,

%U 29,17,3,5,3,29,5,11,5,3,5,29,5,5,3,5,11,3,17,11,11,11,11,5,3,5,11,3,5,3,11

%N Smallest lower twin prime tp such that p + tp + 1 is prime. p ranges over the prime numbers.

%C Conjecture: For all primes p <= n there is always a lower twin prime L less than n such that p+L+1 is prime.

%e 29 is the 9th odd prime. 29+3+1, 29+5+1 are not prime. 29+11+1 is prime, so a(9) = 11 the smallest lower twin prime satisfying the definition for prime 29.

%o (PARI) g(n) = ct=0;for(x=2,n,p1=prime(x);for(y=1,n,p2=twinl(y);z=p1+p2+1;

%o if(isprime(z),ct++;print1(p2",");break)));ct

%K nonn

%O 1,1

%A _Cino Hilliard_, Nov 21 2008