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A193051 Primes p such that 12*p^2-1 and 16*p^3-1 are also primes. 1

%I #20 Sep 08 2022 08:45:58

%S 2,3,17,29,107,167,173,599,1667,1889,2129,3407,3539,3797,3863,5189,

%T 6779,6983,7529,8849,11399,11519,11657,12227,12437,12809,13217,14153,

%U 15227,16223,16607,17609,21683,21863,22193,23789,25127

%N Primes p such that 12*p^2-1 and 16*p^3-1 are also primes.

%C Primes p such that 3*(2p)^2-1 (see A089681) and 2*(2p)^3-1 are primes.

%H Vincenzo Librandi, <a href="/A193051/b193051.txt">Table of n, a(n) for n = 1..1000</a>

%e For p=2, 2 is a prime number, 12*2^2-1=47 is a prime number and 16*2^3-1=127 is a prime number.

%e For p=3, 3 is a prime number, 12*3^2-1=109 is a prime number and 16*3^3-1=431 is a prime number.

%t fQ[n_] := PrimeQ[12 n^2 - 1] && PrimeQ[16 n^3 - 1]; Select[ Prime@ Range@ 3000, fQ] (* _Robert G. Wilson v_, Aug 08 2011 *)

%t Select[Prime[Range[5000]], PrimeQ[12 #^2 - 1] && PrimeQ[16 #^3 - 1]&] (* _Vincenzo Librandi_, Apr 10 2013 *)

%o (Magma) [p: p in PrimesUpTo(26000)|IsPrime(12*p^2-1) and IsPrime(16*p^3-1)]; // _Vincenzo Librandi_, Apr 10 2013

%Y Cf. A158463.

%K nonn,easy

%O 1,1

%A _Juri-Stepan Gerasimov_, Jul 15 2011

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Last modified April 24 03:08 EDT 2024. Contains 371918 sequences. (Running on oeis4.)