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A074691
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Squarefree Fibonacci numbers with odd number of prime factors (mu(n)=-1).
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5
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2, 3, 5, 13, 89, 233, 610, 987, 1597, 10946, 28657, 514229, 3524578, 9227465, 24157817, 39088169, 63245986, 433494437, 701408733, 1134903170, 1836311903, 2971215073, 7778742049, 20365011074, 365435296162, 591286729879
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Agrees for a long time with sequence of Fibonacci numbers whose number of divisors is a Fibonacci number.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..100
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EXAMPLE
| 610 belongs to the sequence because has 3 prime factors (2, 5, 61); it also has 8 divisors (1 2 5 10 61 122 305 610).
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MAPLE
| with(combinat, fibonacci): m2_fib := proc(n); if (numtheory[mobius](fibonacci(n))=-1) then RETURN(fibonacci(n)); fi; end: seq(m2_fib(i), i=1..100);
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MATHEMATICA
| Select[Fibonacci[Range[80]], SquareFreeQ[#]&&MoebiusMu[#]==-1&] (* From Harvey P. Dale, Aug 23 2011 *)
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CROSSREFS
| Cf. A000045.
Cf. A022307, A075735
Sequence in context: A074394 A056162 A001685 * A139589 A152114 A139095
Adjacent sequences: A074688 A074689 A074690 * A074692 A074693 A074694
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KEYWORD
| easy,nice,nonn
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AUTHOR
| Felice Russo (frusso(AT)micron.com), Sep 03 2002
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EXTENSIONS
| More terms from Jani Melik (jani_melik(AT)hotmail.com), Oct 07 2002
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