A396898 Indices k such that prime(k) + 2*prime(k+1) is prime.

2, 3, 4, 5, 6, 13, 14, 17, 24, 26, 27, 30, 31, 41, 42, 43, 44, 48, 53, 57, 59, 62, 63, 64, 65, 68, 72, 82, 83, 92, 94, 98, 109, 112, 115, 122, 137, 138, 142, 143, 150, 152, 153, 155, 156, 157, 158, 159, 162, 163, 171, 172, 175, 178, 186, 190, 193, 201, 204, 212

Offset

1,1

Links

James C. McMahon, Table of n, a(n) for n = 1..10000

Example

2 is a term since prime(2) + 2*prime(3) = 3 + 10 = 13, which is prime.
7 is not a term since prime(7) + 2*prime(8) = 17 + 38 = 55, not prime.

Mathematica

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

Prog

(Python)
from sympy import prime, isprime
def q(k): return isprime(prime(k) + 2 * prime(k + 1))
print([k for k in range(1, 213) if q(k)])

Crossrefs

Cf. A094105, A175914, A094104, A000040.

Sequence in context: A171597 A086185 A072564 * A223938 A222194 A057224

Adjacent sequences: A396895 A396896 A396897 * A396899 A396901 A396903

Keyword

nonn

Author

James C. McMahon and Vincenzo Manto, Jun 09 2026

Status

approved