A049494 -id:A049494 - cp's OEIS frontend

A049495 a(n) and a(n)+4^k are primes at least for k=1,2,3,4,5.

7, 37, 163, 9157, 9277, 15667, 53593, 56893, 111577, 135193, 137383, 142543, 305407, 467527, 470647, 476023, 480043, 527377, 607093, 671353, 761377, 817147, 885943, 891643, 904663, 1080073, 1116637, 1140847, 1172803, 1233523

Offset: 1

Labos Elemer

nonn

			7, 7+4=11, 7+16=23, 7+64=71, 7+256=263, 7+1024=1031 are all primes; the smallest such a sextuple is {7,11,23,71,263,1031}.

Michael De Vlieger, Table of n, a(n) for n = 1..1000

Cf. A023200, A049492-A049494, A049496-A049500.

Select[Prime@ Range[10^5], Function[p, AllTrue[Range@ 5, PrimeQ[p + 4^#] &]]] (* Michael De Vlieger, Aug 09 2017 *)

isok(n) = isprime(n) && isprime(n+4) && isprime(n+16) && isprime(n+64) && isprime(n+256) && isprime(n+1024); \\ Michel Marcus, Dec 22 2013

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

Original entry on oeis.org

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

K. D. Bajpai, Sep 20 2014

			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).

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

Cf. A000040, A049494, A049495.

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

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

cp's OEIS Frontend

A049495 a(n) and a(n)+4^k are primes at least for k=1,2,3,4,5.

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