A396898 - OEIS

%I #10 Jun 13 2026 23:22:02

%S 2,3,4,5,6,13,14,17,24,26,27,30,31,41,42,43,44,48,53,57,59,62,63,64,

%T 65,68,72,82,83,92,94,98,109,112,115,122,137,138,142,143,150,152,153,

%U 155,156,157,158,159,162,163,171,172,175,178,186,190,193,201,204,212

%N Indices k such that prime(k) + 2*prime(k+1) is prime.

%H James C. McMahon, <a href="/A396898/b396898.txt">Table of n, a(n) for n = 1..10000</a>

%e 2 is a term since prime(2) + 2*prime(3) = 3 + 10 = 13, which is prime.

%e 7 is not a term since prime(7) + 2*prime(8) = 17 + 38 = 55, not prime.

%t q[k_]:=PrimeQ[Prime[k]+2Prime[k+1]];Select[Range[300],q[#]&]

%o (Python)

%o from sympy import prime, isprime

%o def q(k): return isprime(prime(k) + 2 * prime(k + 1))

%o print([k for k in range(1, 213) if q(k)])

%Y Cf. A094105, A175914, A094104, A000040.

%K nonn

%O 1,1

%A _James C. McMahon_ and _Vincenzo Manto_, Jun 09 2026