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A228145 Numbers k such that 2*Fibonacci(k) - 1 is prime. 2

%I #27 Sep 08 2022 15:57:47

%S 3,4,8,9,10,16,18,31,34,39,41,42,55,68,79,90,95,97,114,122,148,151,

%T 160,209,265,320,329,441,457,516,529,632,640,682,712,791,1056,1169,

%U 1632,1943,2200,2279,2468,2698,2921,2996,3129,3140,3656,3960,4889,5560,5895

%N Numbers k such that 2*Fibonacci(k) - 1 is prime.

%H Jorge Coveiro, <a href="/A228145/b228145.txt">Table of n, a(n) for n = 1..62</a> (first 55 terms from Vincenzo Librandi)

%t Select[Range[2000], PrimeQ[2 Fibonacci[#] - 1]&]

%o (Magma) [n: n in [1..1700] | IsPrime(2*Fibonacci(n)-1)];

%o (PARI) is(n)=ispseudoprime(2*fibonacci(n)-1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A000045, A124067.

%K nonn

%O 1,1

%A _Vincenzo Librandi_, Aug 13 2013

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Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)