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A139045
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Largest proper divisor of the Fibonacci numbers > 1.
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2
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1, 1, 1, 4, 1, 7, 17, 11, 1, 72, 1, 29, 305, 329, 1, 1292, 113, 2255, 5473, 199, 1, 23184, 15005, 521, 98209, 105937, 1, 416020, 2417, 726103, 1762289, 3571, 1845493, 7465176, 330929, 1056437, 31622993, 34111385
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,4
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COMMENTS
| See the list of divisors of positive Fibonacci numbers in the triangle A133021.
See the largest proper divisor of n in A032742.
Fibonacci(1)=Fibonacci(2)=1 do not have proper divisors. - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 18 2008
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FORMULA
| a(n) = A032742(A000045(n+2)).
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EXAMPLE
| a(7)=17 because n=7 and 7+2=9 and the 9th Fibonacci number is 34 and the divisors of 34 are 1, 2, 17, 34, then the largest proper divisor of 34 is 17.
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MAPLE
| with(combinat): with(numtheory): a:=proc(n) options operator, arrow: op(tau(fibonacci(n))-1, divisors(fibonacci(n))) end proc: seq(a(n), n=3..40); - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 18 2008
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CROSSREFS
| Cf. A000045, A032742, A133021, A133028, A134708.
Sequence in context: A108906 A193842 A134250 * A084884 A143320 A089146
Adjacent sequences: A139042 A139043 A139044 * A139046 A139047 A139048
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KEYWORD
| nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Apr 23 2008
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), May 18 2008
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