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A001578 Smallest primitive prime factor of Fibonacci number F(n).
(Formerly M0603 N0217)
+0
8
1, 1, 2, 3, 5, 1, 13, 7, 17, 11, 89, 1, 233, 29, 61, 47, 1597, 19, 37, 41, 421, 199, 28657, 23, 3001, 521, 53, 281, 514229, 31, 557, 2207, 19801, 3571, 141961, 107, 73, 9349, 135721, 2161, 2789, 211, 433494437, 43, 109441, 139, 2971215073, 1103, 97, 101 (list; graph; listen)
OFFSET

1,3

COMMENT

A Fibonacci number can have more than one primitive factor; the primitive factors of F(19) are 37 and 113.

REFERENCES

D. Jarden, On the greatest primitive divisors of Fibonacci and Lucas numbers with prime-power subscripts, Fib. Quart. 1(#3) (1963), 15-31.

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

T. D. Noe, Table of n, a(n) for n=1..1000 (using Blair Kelly's data)

Blair Kelly, Fibonacci and Lucas Factorizations

MATHEMATICA

prms={}; Table[f=First/@FactorInteger[Fibonacci[n]]; p=Complement[f, prms]; prms=Join[prms, p]; If[p=={}, 1, First[p]], {n, 50}]

CROSSREFS

Cf. A086597 (number of primitive prime factors in F(n)).

Sequence in context: A132597 A030335 A030790 this_sequence A111141 A094122 A082117

Adjacent sequences: A001575 A001576 A001577 this_sequence A001579 A001580 A001581

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

Edited by T. D. Noe (noe(AT)sspectra.com), Apr 15 2004

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Last modified November 23 10:40 EST 2009. Contains 167421 sequences.


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