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A039595
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Positive Fibonacci numbers that are also triangular numbers.
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5
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OFFSET
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1,2
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COMMENTS
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Vern Hoggatt conjectured and Luo Ming confirmed that these are all the terms. - Tomohiro Yamada, Sep 23 2017
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REFERENCES
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J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 55, p. 20, Ellipses, Paris 2008.
D. Wells, Curious and interesting numbers, Penguin Books, p. 108
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LINKS
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MATHEMATICA
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Union[Select[Fibonacci[Range[20]], OddQ[Sqrt[8#+1]]&]] (* Harvey P. Dale, Jan 17 2015 *)
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CROSSREFS
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KEYWORD
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nonn,fini,full
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AUTHOR
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STATUS
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approved
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