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.

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, 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, 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

Offset

1,2

Links

Zak Seidov, Table of n, a(n) for n = 1..1000

Example

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.

Mathematica

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 *)

Crossrefs

Sequence in context: A056881 A260322 A286540 * A184158 A060779 A324650

Adjacent sequences: A229977 A229978 A229979 * A229981 A229982 A229983

Keyword

nonn

Author

Zak Seidov, Oct 05 2013

Extensions

Typo in name and example fixed by Rémy Sigrist, May 14 2017

Status

approved