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Least prime p such that p + previousprime(p) is a multiple of n.
1

%I #10 Feb 09 2015 23:40:23

%S 3,5,7,5,3,7,23,5,11,17,101,7,29,23,17,59,37,11,79,31,23,101,71,13,53,

%T 29,83,43,349,17,97,67,101,37,107,19,113,79,41,61,211,23,89,157,47,71,

%U 283,73,443,53,103,29,641,83,167,59,229,349,239,31,613,97,317,67,197,101,137,37,71,107,431,73

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

%C For examples see A254862.

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

%Y Cf. A254862.

%K nonn

%O 1,1

%A _Zak Seidov_, Feb 09 2015