login
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
OFFSET
1,2
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
KEYWORD
nonn
AUTHOR
Zak Seidov, Mar 29 2014
STATUS
approved