A274987 - OEIS

%I #14 Nov 22 2016 21:21:54

%S 3,5,7,11,13,17,23,31,37,53,59,61,73,79,83,89,101,103,109,127,137,139,

%T 149,173,179,193,223,229,257,263,293,307,313,337,347,349,359,367,389,

%U 397,409,419,439,449,461,467,487,491,521,547,571,577,599,601,619,631

%N Primes p such that A274601(p) is a prime.

%C It is conjectured that the sequence is infinite.

%C This sequence is also the list of primes with k trits that are used in decomposition of 2*3^k into the sum of such two primes. k>=1.

%H Lei Zhou, <a href="/A274987/b274987.txt">Table of n, a(n) for n = 1..10000</a>

%e For p=2, A274601(p) = 4, which is not a prime, so ignore 2.

%e For p=3, A274601(p) = 3, which is a prime, so a(1)=3.

%e For p=5, A274601(p) = 13, which is a prime, so a(2)=5.

%t p = 2; Table[While[p = NextPrime[p]; cp = 2*3^(Floor[Log[3, 2*p - 1]]) - p; !PrimeQ[cp]]; p, {n, 1, 56}]

%Y Cf. A134021, A274601, A002375.

%K nonn,base,easy

%O 1,1

%A _Lei Zhou_, Nov 11 2016