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!)
A239920 Integers n such that 2n^2+1, 2n^3+1 and 2n^4+1 are prime. 2
1, 6, 21, 30, 96, 297, 375, 621, 1359, 1704, 1749, 1761, 3696, 3849, 4467, 8025, 8646, 9834, 11352, 15630, 17397, 17949, 19575, 20274, 27087, 28452, 30504, 32154, 32307, 33666, 35670, 36240, 37785, 37962, 39927, 40617, 42987, 44250, 47559, 49335, 49599 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Zak Seidov, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[0, 50000], PrimeQ[2 #^2 + 1] && PrimeQ[2  #^3 + 1] && PrimeQ[2 #^4 + 1]&] (* Vincenzo Librandi, Mar 30 2014 *)

PROG

(PARI) s=[]; for(n=1, 100000, if(isprime(2*n^2+1) && isprime(2*n^3+1) && isprime(2*n^4+1), s=concat(s, n))); s \\ Colin Barker, Mar 29 2014

CROSSREFS

Subsequence of A239874. Cf. A089001, A168550.

Sequence in context: A287165 A280296 A325407 * A173622 A302868 A064440

Adjacent sequences:  A239917 A239918 A239919 * A239921 A239922 A239923

KEYWORD

nonn

AUTHOR

Zak Seidov, Mar 29 2014

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 July 5 20:01 EDT 2020. Contains 335473 sequences. (Running on oeis4.)