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A241505 Composite integers n satisfying F_n-(n/5) == 0 (mod n), where F_n is the n-th Fibonacci number and (n/5) is the Kronecker symbol. 2
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

Table of n, a(n) for n=1..46.

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

Adjacent sequences:  A241502 A241503 A241504 * A241506 A241507 A241508

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Apr 24 2014

STATUS

approved

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Last modified October 22 19:53 EDT 2019. Contains 328319 sequences. (Running on oeis4.)