|
|
A237814
|
|
Primes p such that 2*p+1 and 2*p+19 are also prime.
|
|
5
|
|
|
2, 5, 11, 41, 89, 131, 191, 251, 419, 431, 641, 809, 1031, 1229, 1409, 1439, 1511, 1559, 1601, 1889, 1901, 1931, 2069, 2351, 2399, 2459, 2699, 2741, 2819, 2939, 3359, 3449, 3491, 3761, 3779, 3911, 4409, 4919, 5081, 5849, 6131, 6449, 6491, 6551, 7079, 7151
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
EXAMPLE
|
11 is in the sequence because 11, 2*11+1 = 23 and 2*11+19 = 41 are all prime.
|
|
MATHEMATICA
|
Select[Prime[Range[8000]], PrimeQ[2 # + 1] && PrimeQ[2 # + 19] &] (* Vincenzo Librandi, Feb 15 2014 *)
|
|
PROG
|
(PARI) s=[]; forprime(p=2, 10000, if(isprime(2*p+1) && isprime(2*p+19), s=concat(s, p))); s
(Magma) [p: p in PrimesUpTo(8000) | IsPrime(2*p+1) and IsPrime(2*p+19)]; // Vincenzo Librandi, Feb 15 2014
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|