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A061899
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Fibonacci numbers that are not squarefree.
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5
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8, 144, 2584, 46368, 75025, 832040, 14930352, 267914296, 4807526976, 12586269025, 86267571272, 225851433717, 1548008755920, 27777890035288, 498454011879264, 2111485077978050, 8944394323791464, 160500643816367088
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) <= Fibonacci(6n) since 4 | Fibonacci(6n). Using other residue classes it can be shown that a(n) >> 1.134^n. How far can this method be taken? [Charles R Greathouse IV, Dec 13 2011]
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LINKS
| Harry J. Smith, Table of n, a(n) for n = 1..87
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EXAMPLE
| 144 and 2584 are Fibonacci numbers (A000045) and are not squarefree: 144 = (2^4)(3^2), 2584 = (2^3)(17)(19).
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MATHEMATICA
| a={}; Do[f=Fibonacci[n]; If[!SquareFreeQ[f], AppendTo[a, f]], {n, 30}]; a (* Vladimir Orlovsky, Jul 23 2008 *)
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PROG
| (PARI) { n=0; h=g=1; for (i=0, 375, f=g + h; h=g; g=f; if (!issquarefree(f), write("b061899.txt", n++, " ", f)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 28 2009]
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CROSSREFS
| Cf. A000045, A061305.
Sequence in context: A180357 A112464 A065409 * A134492 A067421 A124059
Adjacent sequences: A061896 A061897 A061898 * A061900 A061901 A061902
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KEYWORD
| nonn
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AUTHOR
| Asher Auel (asher.auel(AT)reed.edu), May 20 2001
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