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 A143427 a(n)=least prime == -1 mod 6 such that q(n)*(q(n)+a(n))-1 is prime with q(i)=i-th prime == 1 mod 6. 4

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

%S 5,5,11,11,5,5,11,23,5,11,17,41,23,5,11,17,29,17,17,11,47,41,11,11,41,

%T 11,29,41,5,11,29,17,11,5,47,17,17,53,11,5,17,17,47,29,11,23,11,5,17,

%U 5,17,29,11,17,29,11,17,5,11,17,5,17,17,29,17,17,5,23,23,11,113,17,113,5

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

%H Pierre CAMI, <a href="/A143427/b143427.txt">Table of n, a(n) for n = 1..10000</a>

%e q(1)=7, 7*(7+5)-1=83 prime, 5 prime == -1 mod 6 so a(1)=5

%e q(2)=13, 13*(13+5)-1=233 prime, so a(2)=5

%e q(3)=19, 19*(19+5)-1=455 composite 19*(19+11)-1=569 prime, 11 prime == -1 mod 6 so a(3)=11

%Y Cf. A143428, A143429, A143430.

%K nonn

%O 1,1

%A _Pierre CAMI_, Aug 14 2008

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Last modified December 10 18:13 EST 2023. Contains 367717 sequences. (Running on oeis4.)