A099466 - OEIS

%I #7 Nov 29 2017 02:22:39

%S 2,3,4,5,6,7,11,12,13,14,15,19,20,22,25,30,31,33,34,36,37,38,44,45,47,

%T 49,53,55,58,59,60,63,66,67,73,79,83,87,91,93,95,98,105,107,113,115,

%U 118,122,123,127,131,135,141,144,145,147,150,153,160,162,165,167,172,177

%N Numbers n such that 3*prime(n) + prime(n+1) - 3 is prime.

%H Robert Israel, <a href="/A099466/b099466.txt">Table of n, a(n) for n = 1..10000</a>

%e a(2)=4 since 3*prime(4) + prime(5) - 3 = 3*7 + 11 - 3 = 29 is prime.

%p P:= select(isprime, [2,seq(i,i=3..10^4,2)]):

%p select(n -> isprime(3*P[n]+P[n+1]-3), [$1..nops(P)-1]); # _Robert Israel_, Nov 29 2017

%K nonn

%O 1,1

%A _Giovanni Teofilatto_, Nov 18 2004

%E Corrected and extended by _Rick L. Shepherd_, Nov 24 2004