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A190278 Number of decimal digits in LCM of Fibonacci sequence {F_1, ..., F_n}. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Implicitly in Mathematics Teacher, Problem 15, pp. 684-685, May 2011.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A055642(A035105(n)) = floor(log_10(10*A035105(n))).

EXAMPLE

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.

MAPLE

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

PROG

(PARI) a(n) = #Str(lcm(vector(n, k, fibonacci(k)))); \\ Michel Marcus, Mar 13 2018

CROSSREFS

Cf. A000045, A035105, A055642.

Sequence in context: A067175 A225804 A049809 * A254636 A165763 A193838

Adjacent sequences:  A190275 A190276 A190277 * A190279 A190280 A190281

KEYWORD

nonn,base

AUTHOR

Jonathan Vos Post, May 07 2011

STATUS

approved

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Last modified May 24 10:48 EDT 2019. Contains 323529 sequences. (Running on oeis4.)