login
A107312
Primes p such that p + 2 and p^2 + 2^2 are primes.
1
3, 5, 17, 137, 347, 827, 2087, 2687, 3557, 3917, 4517, 4967, 5477, 5657, 5867, 6827, 7457, 7547, 7877, 8087, 8537, 8597, 10037, 10427, 10937, 12107, 12377, 13397, 13877, 16067, 17837, 17987, 19427, 19697, 20507, 20717, 20807, 22367, 22637
OFFSET
1,1
COMMENTS
Primes are lesser twins. Except a(1) and a(2), all a(n) == 7(mod 10).
LINKS
MAPLE
select(p -> isprime(p) and isprime(p+2) and isprime(p^2+4), [seq(2*i+1, i=1..10000)]); # Robert Israel, Aug 11 2014
MATHEMATICA
Select[Prime[Range[3000]], PrimeQ[ #+2]&&PrimeQ[ #^2+4]&]
PROG
(Magma) [p: p in PrimesUpTo(25000)| IsPrime(p+2) and IsPrime(p^2+4)] // Vincenzo Librandi, Jan 29 2011
(PARI) a(n)=isprime(n) && isprime(n+2) && isprime(n^2+4) \\ Edward Jiang, Aug 08 2014
CROSSREFS
Cf. A045637.
Sequence in context: A288376 A096178 A348430 * A083213 A171271 A056826
KEYWORD
nonn
AUTHOR
Zak Seidov, May 21 2005
STATUS
approved