login
A235871
Primes p such that p+2, p+24 and p+246 are also primes.
1
5, 17, 107, 617, 857, 1277, 1487, 2087, 3167, 3557, 4217, 6947, 7457, 7877, 10067, 12917, 13217, 14387, 15137, 17657, 20897, 21317, 22367, 22697, 27407, 27527, 27917, 28547, 29207, 29387, 30467, 31727, 32117, 33287, 33617, 35507, 36107, 47657, 49367, 49787
OFFSET
1,1
COMMENTS
All the terms in the sequence are congruent to 5 mod 6.
The constants in the definition (2, 24 and 246) are the concatenation of first even digits 2,4 and 6.
LINKS
EXAMPLE
a(2) = 17 is a prime: 17+2 = 19, 17+24 = 41 and 17+246 = 263 are also prime.
a(3) = 107 is a prime: 107+2 = 119, 107+24 = 131 and 107+246 = 353 are also prime.
MAPLE
KD:= proc() local a, b, d, e; a:= ithprime(n); b:=a+2; d:=a+24; e:=a+246; if isprime(b) and isprime(d) and isprime(e) then return (a) :fi; end: seq(KD(), n=1..15000);
MATHEMATICA
KD = {}; Do[p = Prime[n]; If[PrimeQ[p + 2] && PrimeQ[p + 24] && PrimeQ[p + 246], AppendTo[KD, p]], {n, 15000}]; KD
c = 0; p = Prime[n]; Do[If[PrimeQ[p + 2] && PrimeQ[p + 24] && PrimeQ[p + 246], c = c + 1; Print[c, " ", Prime[n]]], {n, 1, 5000000}]; (* b - file *)
PROG
(PARI) s=[]; forprime(p=2, 50000, if(isprime(p+2) && isprime(p+24) && isprime(p+246), s=concat(s, p))); s \\ Colin Barker, Apr 21 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Apr 21 2014
STATUS
approved