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A190278
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Number of decimal digits in LCM of Fibonacci sequence {F_1,...,F_n}.
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1
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1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 15, 17, 20, 21, 25, 27, 29, 31, 36, 38, 42, 44, 48, 51, 56, 58, 64, 67, 72, 75, 80, 83, 90, 94, 99, 103, 111, 113, 122, 126, 131, 136, 145, 149, 157, 162, 168, 173, 184, 188, 196, 201, 209, 215
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OFFSET
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1,5
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COMMENTS
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Implicitly in Mathematics Teacher, Problem 15, pp. 684-685, May 2011.
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LINKS
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Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n) = A055642(A035105(n)) = floor[log10(10*A035105(n))].
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EXAMPLE
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a(4) = 1 because LCM{F_1,F_2,F_3,F_4} = 6 has one decimal digit.
a(19) = 25 because LCM{F_1,...,F_19} = 2679944489486672512824720 has 25 decimal digits.
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MAPLE
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with(combinat):
b:= proc(n) option remember;
`if` (n=1, 1, ilcm (b(n-1), fibonacci(n)))
end:
a:= n-> length(b(n)):
seq (a(n), n=1..80); # Alois P. Heinz, Jul 28 2011
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CROSSREFS
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Cf. A000045, A035105, A055642.
Sequence in context: A048856 A067175 A049809 * A165763 A193838 A178877
Adjacent sequences: A190275 A190276 A190277 * A190279 A190280 A190281
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KEYWORD
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nonn,base,changed
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AUTHOR
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Jonathan Vos Post, May 07 2011
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STATUS
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approved
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