A377318 Numbers k such that prime(k), prime(k)+6, prime(k)+12, and prime(k)+18 are primes.

3, 5, 13, 18, 54, 110, 116, 182, 234, 252, 271, 284, 351, 387, 464, 541, 551, 682, 709, 717, 741, 821, 829, 1171, 1417, 1448, 1510, 1594, 1711, 1726, 1842, 1853, 2009, 2086, 2209, 2297, 2408, 2600, 2680, 2876, 2924, 2930, 3253, 3303, 3437, 3977, 4384, 4431

Offset

1,1

Links

Table of n, a(n) for n=1..48.

Formula

a(n) = pi(A023271(n)).

Maple

5 is in this sequence because: prime(5) = 11 and 11+6=17, 11+12=23, and 11+18=29 are all primes.

Mathematica

Select[Range[1, PrimePi[50000]], PrimeQ[Prime[#] + 6] && PrimeQ[Prime[#] + 12] && PrimeQ[Prime[#] + 18] &]

Prog

(PARI) for(k=1, primepi(50000), p = prime(k); if(isprime(p+6) && isprime(p+12) && isprime(p+18), print(k)))

Crossrefs

Cf. A000040, A000720, A023271.

Subsequence of A377317.

Sequence in context: A002716 A046154 A180120 * A075704 A045413 A378422

Adjacent sequences: A377315 A377316 A377317 * A377319 A377320 A377321

Keyword

nonn

Author

Kritsada Moomuang, Oct 24 2024

Status

approved