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Numbers k such that 1+k, 1+k^2, 1+k^4 and 1+k^16 are all prime.
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%I #21 Sep 08 2022 08:45:56

%S 1,2,690,33190,57106,77140,135606,258990,303430,331140,337536,359230,

%T 375646,455526,458326,493396,548226,550540,585106,602056,659250,

%U 680830,742306,800406,827680,870240,918340,925390,968320,1203100,1273890,1455526,1497576,1605016

%N Numbers k such that 1+k, 1+k^2, 1+k^4 and 1+k^16 are all prime.

%C Subsequence of A070325, which itself is a subsequence of A070689, which itself is a subsequence of A006093.

%e a(3) = 690 = A070689(32) = A070325(11) = A006093(125).

%o (Magma) [n: n in [0..7000000]| IsPrime(1+n) and IsPrime(1+n^2) and IsPrime(1+n^4) and IsPrime(1+n^16)]; // _Vincenzo Librandi_, Apr 11 2011

%K nonn

%O 1,2

%A _Zak Seidov_, Apr 09 2011

%E a(1) = 1 prepended by _Vincenzo Librandi_, Apr 11 2011