A247590 Primes p such that p + 6^k is also prime at least for k = 1, 2, 3 and 4.

7, 11, 23, 131, 157, 193, 227, 271, 331, 571, 947, 977, 1013, 1087, 1283, 1453, 1657, 1871, 2341, 2671, 2693, 3607, 3637, 3691, 4013, 4951, 5407, 5653, 6211, 6353, 6653, 6827, 6977, 6991, 7541, 7717, 8053, 8081, 8537, 9203, 9613, 9643, 10853, 11113, 11251, 11933

Offset

1,1

Links

K. D. Bajpai, Table of n, a(n) for n = 1..12638

Example

a(1) = 7 is prime. 7 + 6^1 = 13, 7 + 6^2 = 43, 7 + 6^3 = 223 and 7 + 6^4 = 1303 are also prime. It is the smallest such set of 5 primes; (Quintet).

Mathematica

Select[k = {1, 2, 3, 4}; Prime[Range[500]], And @@ PrimeQ[# + 6^k] &]

Prog

(PARI)
forprime(p=1, 10^4, c=1; for(k=1, 4, if(!isprime(p+6^k), c--; break)); if(c, print1(p, ", "))) \\ Derek Orr, Sep 20 2014

Crossrefs

Cf. A000040, A049494, A049495.

Sequence in context: A076855 A160054 A359414 * A027830 A134043 A102373

Adjacent sequences: A247587 A247588 A247589 * A247591 A247592 A247593

Keyword

nonn,easy

Author

K. D. Bajpai, Sep 20 2014

Status

approved