A086381 Numbers n such that p=n^2+2 and p+2 are primes.

1, 3, 15, 33, 45, 57, 117, 147, 243, 255, 303, 375, 423, 447, 453, 477, 573, 753, 837, 897, 903, 1035, 1497, 1905, 2055, 2085, 2193, 2283, 2433, 2487, 2535, 2583, 2757, 2823, 2943, 2955, 3003, 3213, 3285, 3345, 3603, 3657, 3687, 4407, 4575, 4977, 5037, 5043, 5325, 5355, 5367, 5403, 5727

Offset: 1

Author

Zak Seidov, Sep 07 2003

Keywords

• easy
• nonn

Comments

The twin primes are given by A253639 and A085554. Except for the initial term, all a(n)=3 (mod 6). - M. F. Hasler, Jan 16 2015

Links

• M. F. Hasler, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A253639, A085554, A059100, A087475.

Programs

Magma

[n: n in [0..10000]|IsPrime(n^2+2) and IsPrime(n^2+4)] // Vincenzo Librandi, Dec 16 2010

PARI

is_A086381(x)=ispseudoprime(x^2+2)&&ispseudoprime(x^2+4)
forstep(x=1,9999,2,is_A086381(x)&&print1(x",")) \\ M. F. Hasler, Jan 16 2015

Formula

Intersection of A067201 and A007591. - M. F. Hasler, Jan 19 2015

Extensions

More terms from Vincenzo Librandi, Dec 16 2010