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A241505 Composite integers k satisfying F_k-(k/5) == 0 (mod k), where F_k is the k-th Fibonacci number and (k/5) is the Kronecker symbol. 3
25, 60, 120, 125, 180, 240, 300, 323, 360, 377, 480, 540, 600, 625, 660, 720, 840, 900, 960, 1080, 1200, 1320, 1440, 1500, 1620, 1680, 1800, 1860, 1891, 1920, 1980, 2160, 2400, 2460, 2520, 2640, 2700, 2760, 2880, 3000, 3060, 3125, 3240, 3300, 3360, 3420 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Sequence resembles A090820, although they are not identical.
LINKS
Z. H. Sun and Z. W. Sun, Fibonacci numbers and Fermat's last theorem, Acta Arithmetica 60(4) (1992), 371-388.
MATHEMATICA
Select[Range[2, 5000], ! PrimeQ[#] && Mod[Fibonacci[# - JacobiSymbol[#, 5]], #] == 0 &] (* Jean-François Alcover, Apr 24 2014 *)
PROG
(PARI) forcomposite(n=2, 1e4, if(Mod(fibonacci(n-kronecker(n, 5)), n)==0, print1(n, ", ")))
CROSSREFS
Sequence in context: A250191 A163654 A063317 * A090820 A044127 A044508
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Apr 24 2014
STATUS
approved

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Last modified February 27 08:14 EST 2024. Contains 370367 sequences. (Running on oeis4.)