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%I A239920 #12 Mar 30 2014 04:25:15
%S A239920 1,6,21,30,96,297,375,621,1359,1704,1749,1761,3696,3849,4467,8025,
%T A239920 8646,9834,11352,15630,17397,17949,19575,20274,27087,28452,30504,
%U A239920 32154,32307,33666,35670,36240,37785,37962,39927,40617,42987,44250,47559,49335,49599
%N A239920 Integers n such that 2n^2+1, 2n^3+1 and 2n^4+1 are prime.
%H A239920 Zak Seidov, <a href="/A239920/b239920.txt">Table of n, a(n) for n = 1..1000</a>
%t A239920 Select[Range[0, 50000], PrimeQ[2 #^2 + 1] && PrimeQ[2  #^3 + 1] && PrimeQ[2 #^4 + 1]&] (* _Vincenzo Librandi_, Mar 30 2014 *)
%o A239920 (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
%Y A239920 Subsequence of A239874. Cf. A089001, A168550.
%K A239920 nonn
%O A239920 1,2
%A A239920 _Zak Seidov_, Mar 29 2014

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