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A122060
Position in decimal expansion of 1/n where repetition begins.
1
2, 3, 2, 4, 3, 3, 7, 5, 2, 3, 3, 4, 7, 8, 3, 6, 17, 3, 19, 4, 7, 4, 23, 5, 4, 8, 4, 11, 29, 3
OFFSET
1,1
COMMENTS
If 1/n = 0.XYYYYY... then sequence gives index of first digit of the second Y.
a(4) = 4 and a(p) = p for primes p = {7, 17, 19, 23, 29, 47, 59, 61, 97, ...} = A001913(n) Cyclic numbers: primes with primitive root 10. - Alexander Adamchuk, Jan 28 2007
FORMULA
a(n)=A121341(n)+2 if 1/n terminates, else a(n)=A121341(n)+1. - R. J. Mathar, Sep 20 2006
EXAMPLE
a(4) = 4 because in 0.2500 the zero begins repeating at the fourth position.
a(17) = 17 because 0.05882352941176470588... begins repeating at the 17th position.
CROSSREFS
Sequence in context: A316714 A135817 A360485 * A088939 A324183 A335616
KEYWORD
nonn,base
AUTHOR
Ben Paul Thurston, Sep 14 2006
STATUS
approved