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A229980 Smallest integer m > 0 such that p(n) + m*p(n + 1) and m*p(n) + p(n + 1) are prime, p(n) = n-th prime. 2

%I #10 May 14 2017 11:54:03

%S 1,2,2,6,6,2,14,6,6,8,10,6,14,12,10,16,2,6,14,6,10,6,4,20,14,6,2,6,44,

%T 2,26,34,20,6,30,6,10,8,42,54,8,6,20,18,20,52,6,2,14,6,6,20,2,16,10,6,

%U 2,34,14,14,18,14,74,44,20,26,126,2,26,6,10,20,22,4,6,10,126,54,8,8,12,18,66,6,24,4,56,20,54,14,4,14,6,2,14,4,4,176,4,4,8

%N Smallest integer m > 0 such that p(n) + m*p(n + 1) and m*p(n) + p(n + 1) are prime, p(n) = n-th prime.

%H Zak Seidov, <a href="/A229980/b229980.txt">Table of n, a(n) for n = 1..1000</a>

%e n=2, m=2: p(n) + m*p(n + 1) = 3 + 2*5 = 13 and m*p(n) + m*p(n + 1) = 2*3 + 5 = 11 are prime.

%t lim=100; Table[m = 1; While[! PrimeQ[m*Prime[n] + Prime[n + 1]] || ! PrimeQ[Prime[n] + m*Prime[n + 1]], m++]; m, {n, lim}] (* _Zak Seidov_, Oct 05 2013 *)

%K nonn

%O 1,2

%A _Zak Seidov_, Oct 05 2013

%E Typo in name and example fixed by _Rémy Sigrist_, May 14 2017

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