login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A176978 Numbers n such that n^2 + 13 and n^2 + 13^2 are primes. 5
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 (list; graph; refs; listen; history; text; internal format)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 14 19:09 EDT 2020. Contains 336483 sequences. (Running on oeis4.)