OFFSET
1,1
LINKS
Karl V. Keller, Jr., Table of n, a(n) for n = 1..10000
EXAMPLE
19 is in the sequence because 19 is prime and 19 + 28 = 47 is also prime.
433 is in the sequence because 433 is prime and 433 + 28 = 461 is also prime.
MAPLE
P:= select(isprime, {seq(2*i+1, i=1..10000)}):
P intersect map(`-`, P, 28);
# if using Maple 11 or earlier, uncomment the next line
# sort(convert(%, list)); # Robert Israel, Dec 14 2014
MATHEMATICA
Select[Prime[Range[250]], PrimeQ[# + 28] &]
PROG
(Magma) [NthPrime(n): n in [1..250] | IsPrime(NthPrime(n)+28)];
(PARI) is(n)=isprime(n)&&isprime(n+28) \\ Anders Hellström, Dec 01 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Dec 14 2014
STATUS
approved