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Numbers k such that 2k^3 + 7 is prime. For k >= 8, bases in which 2007 is prime.
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%I #12 Dec 18 2024 22:41:30

%S 0,2,3,5,6,8,12,17,20,26,27,32,33,36,38,41,47,50,60,65,72,75,78,87,

%T 101,111,122,123,135,137,146,152,156,162,165,173,177,188,191,195,197,

%U 221,243,246,261,267,272,291,303,311,312,321,323,330,332,333,338,362,365

%N Numbers k such that 2k^3 + 7 is prime. For k >= 8, bases in which 2007 is prime.

%t Select[Range[0,365],PrimeQ[2#^3+7]&] (* _James C. McMahon_, Dec 18 2024 *)

%o (PARI) is(n)=isprime(2*n^3+7) \\ _Charles R Greathouse IV_, Jun 13 2017

%K base,nonn,easy

%O 1,2

%A _Zak Seidov_, Jan 01 2007