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A093062 a(n) = Fibonacci(prime(n)) - prime(Fibonacci(n)). 3

%I #34 Sep 08 2022 08:45:13

%S -1,0,2,8,78,214,1556,4108,28518,513972,1345808,24156990,165578670,

%T 433491846,2971210580,53316283380,956722012572,2504730758802,

%U 44945570173074,308061521102198,806515532933562,14472334024479534,99194853094422264,1779979416004150202

%N a(n) = Fibonacci(prime(n)) - prime(Fibonacci(n)).

%C Composition of prime( ) and Fibonacci( ) is not commutative. Does a prime p ever divide Fibonacci(prime(p)) - prime(Fibonacci(p))?

%C Note that a(3) = 2 is the only prime element of the sequence. This is because after 2, all primes are odd; and the Fibonacci number F(n) is even only for n = 3k for some integer k [which relates to the fact that A082115 Fibonacci sequence (mod 3) is periodic with Pisano period 8]. Hence after a(1) = -1, Fibonacci(prime(n)) - prime(Fibonacci(n)) is always the difference of two odd numbers, hence is even. - _Jonathan Vos Post_, Jan 23 2006

%C Is a(i) ever divisible by i? Answer: yes. The quotient is an integer for i = 4, 28 and 30 through 63. - Dennis S. Kluk (mathemagician(AT)ameritech.net), Aug 16 2006

%H Chai Wah Wu, <a href="/A093062/b093062.txt">Table of n, a(n) for n = 1..84</a> (terms 1..41 from Harry J. Smith)

%F a(n) = Fibonacci(prime(n)) - prime(Fibonacci(n)).

%e a(11) = Fibonacci(prime(11)) - prime(Fibonacci(11)) = 1345808.

%t For[i=1, i<61, i++, Print[i, " ", Fibonacci[Prime[i]]-Prime[Fibonacci[i]]]]

%t Table[Fibonacci[Prime[n]]-Prime[Fibonacci[n]],{n,30}] (* _Harvey P. Dale_, Jul 02 2018 *)

%o (PARI) { default(primelimit, 4294965247); for(n=1, 41, a=fibonacci(prime(n)) - prime(fibonacci(n)); write("b093062.txt", n, " ", a); ); } \\ _Harry J. Smith_, Jun 20 2009

%o (Magma) [Fibonacci(NthPrime(n)) - NthPrime(Fibonacci(n)): n in [1..30]]; // _Vincenzo Librandi_, Apr 10 2020

%Y Cf. A000040, A000045, A030427.

%Y Cf. A082115.

%K easy,sign

%O 1,3

%A Dennis S. Kluk (mathemagician(AT)ameritech.net), May 08 2004

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Last modified March 29 04:59 EDT 2024. Contains 371264 sequences. (Running on oeis4.)