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 A000057 Primes dividing all Fibonacci sequences. (Formerly M0856 N0326) 42
 2, 3, 7, 23, 43, 67, 83, 103, 127, 163, 167, 223, 227, 283, 367, 383, 443, 463, 467, 487, 503, 523, 547, 587, 607, 643, 647, 683, 727, 787, 823, 827, 863, 883, 887, 907, 947, 983, 1063, 1123, 1163, 1187, 1283, 1303, 1327, 1367, 1423, 1447, 1487, 1543 (list; graph; refs; listen; history; text; internal format)
 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. Paul Cubre and Jeremy Rouse, Divisibility properties of the Fibonacci entry point, arXiv:1212.6221 [math.NT], 2012. Ron Knott, General Fibonacci Series N. J. A. Sloane, Families of Essentially Identical Sequences, Mar 24 2021 (Includes this sequence) MATHEMATICA Select[Prime[Range], 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 Subsequence of A064414. Cf. A001602, A079346, A106535, A213648. Sequence in context: A002230 A106865 A267504 * A037231 A248525 A082449 Adjacent sequences:  A000054 A000055 A000056 * A000058 A000059 A000060 KEYWORD nonn AUTHOR EXTENSIONS More terms from Don Reble, Nov 14 2006 STATUS approved

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Last modified April 22 19:11 EDT 2021. Contains 343177 sequences. (Running on oeis4.)