OFFSET
1,1
COMMENTS
Primes are lesser twins. Except a(1) and a(2), all a(n) == 7(mod 10).
LINKS
Edward Jiang, Table of n, a(n) for n = 1..1000
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
KEYWORD
nonn
AUTHOR
Zak Seidov, May 21 2005
STATUS
approved