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 A143430 a(n)=least prime == 1 mod 6 such that q(n)*(q(n)+a(n))-1 and q(n)*(q(n)+a(n))+1 are twin primes with q(i)=i-th prime == -1 mod 6. 4

%I #5 Mar 31 2012 13:22:05

%S 7,7,43,13,43,97,43,67,193,157,31,211,61,523,73,241,13,19,97,67,13,67,

%T 157,283,193,79,157,67,151,211,67,13,7,739,109,7,151,157,73,109,61,97,

%U 223,79,157,373,109,211,193,163,67,13,31,229,19,151,31,43,31,199,7,31

%N a(n)=least prime == 1 mod 6 such that q(n)*(q(n)+a(n))-1 and q(n)*(q(n)+a(n))+1 are twin primes with q(i)=i-th prime == -1 mod 6.

%H Pierre CAMI, <a href="/A143430/b143430.txt">Table of n, a(n) for n = 1..10000</a>

%e q(1)=5, 5*(5+7)-1=59 prime, 59 and 61 twin primes so a(1)=7

%e q(2)=11, 11*(11+7)-1=197 prime, 197 and 199 twin primes so a(2)=7

%Y Cf. A143427, A143428, A143429.

%K nonn

%O 1,1

%A _Pierre CAMI_, Aug 14 2008

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Last modified September 26 12:37 EDT 2023. Contains 365657 sequences. (Running on oeis4.)