A241487 Primes p such that p+6, p+666 and p+6666 are also prime.

7, 53, 67, 157, 191, 311, 331, 347, 353, 373, 443, 563, 571, 641, 821, 823, 857, 941, 1033, 1087, 1123, 1283, 1423, 1607, 1621, 1873, 1997, 2011, 2137, 2333, 2383, 2543, 2657, 2677, 2797, 2957, 3301, 3511, 3607, 3671, 3691, 3797, 3847, 4133, 5113, 5147, 5231

Offset

1,1

Comments

The constants in the definition (6, 666 and 6666) are concatenations of the digit 6.

Links

K. D. Bajpai, Table of n, a(n) for n = 1..10000

Example

a(2) = 53 is a prime: 53+6 = 59, 53+666 = 719 and 53+6666 = 6719 are also prime.
a(3) = 67 is a prime: 67+6 = 73, 67+666 = 733 and 67+6666 = 6733 are also prime.

Maple

KD:= proc() local a, b, d, e; a:= ithprime(n); b:=a+2; d:=a+222; e:=a+2222; if isprime(b)and isprime(d)and isprime(e)  then return (a) :fi; end: seq(KD(), n=1..5000);

Mathematica

KD = {}; Do[p = Prime[n]; If[PrimeQ[p + 6] && PrimeQ[p + 666] && PrimeQ[p + 6666], AppendTo[KD, p]], {n, 5000}]; KD
(*For the b-file*) c = 0; p = Prime[n]; Do[If[PrimeQ[p + 6] && PrimeQ[p + 666] && PrimeQ[p + 6666], c = c + 1; Print[c, "  ", p]], {n, 1, 2*10^6}];

Prog

(PARI) s=[]; forprime(p=2, 6000, if(isprime(p+6) && isprime(p+666) && isprime(p+6666), s=concat(s, p))); s \\ Colin Barker, Apr 25 2014

Crossrefs

Cf. A000040, A023200, A046136, A230223, A236302, A236304, A237890, A241485.

Sequence in context: A301485 A357362 A224501 * A236688 A239941 A253123

Adjacent sequences: A241484 A241485 A241486 * A241488 A241489 A241490

Keyword

nonn

Author

K. D. Bajpai, Apr 23 2014

Status

approved