A143394 - OEIS

%I #8 Jan 19 2019 22:17:50

%S 0,3,0,2,3,2,3,2,109,1291,3,557,211,3,3,7,7,3,2,13,2,5,43,97,2,3,149,

%T 43,5,3,5,13,3,2,7,3,5,197,13,73,7,11,229,23,3,5,3,23,13,2,19,7,5,109,

%U 283,67,7,3,11,13,2,43,2,19,233,7,1061,3,3,149,43,421,11,113,29,7,991,41,61

%N Least prime p such that p*(p + prime(n)) -+ 1 are twin primes, or 0 if no such prime exists.

%C No twin primes of the form p*(p+2) -+ 1 for p prime.

%C Only one pair of twin primes of the form p*(p+3) -+ 1 (it occurs at p=3).

%C No twin primes of the form p*(p+5) -+ 1 for p prime.

%H Pierre CAMI, <a href="/A143394/b143394.txt">Table of n, a(n) for n = 1..12250</a>

%e 3*(3+3) - 1 = 17 and 3*(3+3) + 1 = 19 are twin primes (and 2*(2+3) - 1 = 9 and 2*(2+3) + 1 = 11 are not twin primes) so a(2)=3.

%Y Cf. A143393.

%K nonn

%O 1,2

%A _Pierre CAMI_, Aug 12 2008

%E Edited by _Jon E. Schoenfield_, Jan 19 2019