A239920 Integers n such that 2n^2+1, 2n^3+1 and 2n^4+1 are prime.

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

Author

Zak Seidov, Mar 29 2014

Keywords

• nonn

Links

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

Crossrefs

Subsequence of A239874. Cf. A089001, A168550.

Programs

Mathematica

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

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