OFFSET
1,1
COMMENTS
Here a Fibonacci sequence is a sequence which begins with any two integers and continues using the rule s(n+2) = s(n+1) + s(n). These primes divide at least one number in each such sequence. - Don Reble, Dec 15 2006
Primes p such that the smallest positive m for which Fibonacci(m) == 0 (mod p) is m = p + 1. In other words, the n-th prime p is in this sequence iff A001602(n) = p + 1. - Max Alekseyev, Nov 23 2007
Cubre and Rouse comment that this sequence is not known to be infinite. - Charles R Greathouse IV, Jan 02 2013
Number of terms up to 10^n: 3, 7, 38, 249, 1894, 15456, 130824, 1134404, 10007875, 89562047, .... - Charles R Greathouse IV, Nov 19 2014
These are also the fixed points of sequence A213648 which gives the minimal number of 1's such that n*[n; 1,..., 1, n] = [x; ..., x], where [...] denotes simple continued fractions. - M. F. Hasler, Sep 15 2015
It appears that for n >= 2, all first differences are congruent to 0 (mod 4). - Christopher Hohl, Dec 28 2018
The comment above is equivalent to a(n) == 3 (mod 4) for n >= 2. This is indeed correct. Actually it can be proved that a(n) == 3, 7 (mod 20) for n >= 2. Let p != 2, 5 be a prime, then: A001175(p) divides (p - 1)/2 if p == 1, 9 (mod 20); p - 1 if p == 11, 19 (mod 20); (p + 1)/2 if p == 13, 17 (mod 20). So the remaining cases are p == 3, 7 (mod 20). - Jianing Song, Dec 29 2018
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Christian G. Bower and T. D. Noe, Table of n, a(n) for n = 1..1000
U. Alfred, Primes which are factors of all Fibonacci sequences, Fib. Quart., 2 (1964), 33-38.
B. Avila and T. Khovanova, Free Fibonacci Sequences, arXiv preprint arXiv:1403.4614 [math.NT], 2014 and J. Int. Seq. 17 (2014) # 14.8.5.
D. M. Bloom, On periodicity in generalized Fibonacci sequences, Am. Math. Monthly 72 (8) (1965) 856-861.
H. E. A. Campbell and David L. Wehlau, Zigzag polynomials, Artin's conjecture and trinomials, Finite Fields and Their Applications (2023) Vol. 89, 102198.
Paul Cubre and Jeremy Rouse, Divisibility properties of the Fibonacci entry point, arXiv:1212.6221 [math.NT], 2012.
Ron Knott, General Fibonacci Series.
Rishi Kumar, Kepler Sets of Second-Order Linear Recurrence Sequences Over Q_p, arXiv:2406.05890 [math.NT], 2024. See pp. 2, 7.
N. J. A. Sloane, Families of Essentially Identical Sequences, Mar 24 2021 (Includes this sequence).
MATHEMATICA
Select[Prime[Range[1000]], Function[p, a=0; b=1; n=1; While[b != 0, t=b; b = Mod[(a+b), p]; a=t; n++]; n>p]] (* Jean-François Alcover, Aug 05 2018, after Charles R Greathouse IV *)
PROG
(PARI) select(p->my(a=0, b=1, n=1, t); while(b, t=b; b=(a+b)%p; a=t; n++); n>p, primes(1000)) \\ Charles R Greathouse IV, Jan 02 2013
(PARI) is(p)=fordiv(p-1, d, if(((Mod([1, 1; 1, 0], p))^d)[1, 2]==0, return(0))); fordiv(p+1, d, if(((Mod([1, 1; 1, 0], p))^d)[1, 2]==0, return(d==p+1 && isprime(p)))) \\ Charles R Greathouse IV, Jan 02 2013
(PARI) is(p)=if((p-2)%5>1, return(0)); my(f=factor(p+1)); for(i=1, #f~, if((Mod([1, 1; 1, 0], p)^((p+1)/f[i, 1]))[1, 2]==0, return(0))); isprime(p) \\ Charles R Greathouse IV, Nov 19 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Don Reble, Nov 14 2006
STATUS
approved