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A121090

Period of unit fractions having periodic decimal expansions.

1, 1, 6, 1, 2, 1, 6, 6, 1, 16, 1, 18, 6, 2, 22, 1, 6, 3, 6, 28, 1, 15, 2, 16, 6, 1, 3, 18, 6, 5, 6, 21, 2, 1, 22, 46, 1, 42, 16, 6, 13, 3, 2, 6, 18, 28, 58, 1, 60, 15, 6, 6, 2, 33, 16, 22, 6, 35, 1, 8, 3, 1, 18, 6, 6, 13, 9, 5, 41, 6, 16, 21, 28, 2, 44, 1, 6, 22, 15, 46, 18, 1, 96, 42, 2, 4, 16

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OFFSET

0,3

COMMENTS

See A007732, which is the main entry for this sequence.

LINKS

Table of n, a(n) for n=0..86.

FORMULA

a(n) = A007732(A085837(n)). - Kevin Ryde, May 05 2023

EXAMPLE

The first unit fraction considered is 1/3 because both 1/1 and 1/2 have finite decimal expansions.

a(1) = 1 because 1/3=.33333... whose repeating portion, 3, is of length 1.