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A254862 Least prime p such that p + nextprime(p) is a multiple of n. 3

%I

%S 2,3,5,3,2,5,19,3,7,13,97,5,23,19,13,53,31,7,73,29,19,97,67,11,47,23,

%T 79,41,347,13,89,61,97,31,103,17,109,73,37,59,199,19,83,151,43,67,281,

%U 71,439,47,101,23,631,79,163,53,227,347,233,29,607,89,313,61,193,97,131,31,67,103,421,71

%N Least prime p such that p + nextprime(p) is a multiple of n.

%C for k=1..10, a(1000*k) = 2999, 2999, 2999, 21997, 12497, 2999, 10499, 51991, 4493, 29989.

%H Ivan Neretin, <a href="/A254862/b254862.txt">Table of n, a(n) for n = 1..10000</a>

%e 2+3=5=1*5, 3+5=8=2*4, 5+7=12=3*4, 3+5=8=4*1, 2+3=5=5*1, 5+7=12=6*2, 19+23=42=7*6, 3+5=8=8*1, 7+11=18=9*2, 13+17=30=10*3.

%t s={};Do[p=2;q=3;While[Mod[p+q,n]>0,p=q;q=NextPrime[q]];AppendTo[s,p],{n,50}];s

%o (PARI) s=[];for(n=1,50,p=2;q=3;while((p+q)%n>0,p=q;q=nextprime(q+1));s=concat(s,p));s

%Y Cf. A254863.

%K nonn

%O 1,1

%A _Zak Seidov_, Feb 09 2015

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Last modified May 28 03:04 EDT 2020. Contains 334671 sequences. (Running on oeis4.)