A176978 Numbers n such that n^2 + 13 and n^2 + 13^2 are primes.

2, 10, 12, 28, 42, 60, 68, 108, 110, 122, 142, 180, 198, 200, 268, 282, 340, 378, 380, 418, 430, 488, 500, 502, 530, 612, 742, 788, 802, 838, 840, 912, 942, 948, 952, 1010, 1080, 1102, 1148, 1232, 1270, 1428, 1452, 1472, 1502, 1522, 1538, 1720, 1778, 1830

Offset

1,1

Comments

Numbers are subsequence of A113536 and A176969

See comments and references of A176969

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

2^2 + 13 = 17 = prime(7), 2^2 + 13^2 = 173 = prime(40), 2 is first term.

Mathematica

Select[Range[2000], AllTrue[#^2+{13, 13^2}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 28 2015 *)

Prog

(PARI) isok(n) = isprime(n^2 + 13) && isprime(n^2 + 13^2); \\ Michel Marcus, Aug 27 2013

Crossrefs

Cf. A000040, A000290, A056899, A113536, A176371, A176969.

Sequence in context: A004686 A080139 A055701 * A186630 A154391 A035928

Adjacent sequences: A176975 A176976 A176977 * A176979 A176980 A176981

Keyword

nonn

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Apr 30 2010

Status

approved