

A122060


Position in decimal expansion of 1/n where repetition begins.


0



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
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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


LINKS

Table of n, a(n) for n=1..30.


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

Cf. A001913, A002371.
Sequence in context: A072645 A316714 A135817 * A088939 A324183 A004596
Adjacent sequences: A122057 A122058 A122059 * A122061 A122062 A122063


KEYWORD

nonn,base


AUTHOR

Ben Paul Thurston, Sep 14 2006


STATUS

approved



