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A035335 a(n) = smallest number m such that n appears in decimal expansion of 1/m. 1
6, 4, 3, 7, 2, 6, 7, 7, 11, 10, 9, 8, 23, 7, 19, 6, 17, 49, 21, 5, 19, 31, 13, 29, 4, 19, 29, 7, 17, 13, 19, 31, 3, 23, 17, 19, 27, 26, 23, 25, 17, 7, 23, 29, 22, 26, 17, 29, 51, 2, 29, 17, 26, 22, 18, 23, 7, 17, 47, 23, 21, 16, 19, 17, 23, 6, 49, 19, 13, 17, 7, 29, 19, 47, 29, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

David W. Wilson, Table of n, a(n) for n = 1..10000 (n <= 200 from R. J. Mathar)

EXAMPLE

a(13)=23 since 1/23=.04347826086956521739{13}... is the first to contain 13.

1/6=.16666... so a(n)=6 for n=1,6,16,66,166,666,1666,6666, ...

MATHEMATICA

foundQ[n_, m_] := (idn = IntegerDigits[n]; ln = Length[idn]; rdm = Most[ Flatten[ RealDigits[1/m, 10, lm = 2* Length[ Flatten[ RealDigits[1/m]]]]]]; found = False; Do[If[idn === Take[rdm, {k, k+ln-1}], found = True; Break[]], {k, 1, lm-ln+1}]; found); a[n_] := (m = 2; While[ True, If[foundQ[n, m], Break[], m++]]; m); a[n_ /; n > 1 && IntegerQ[ Log[10, n]]] := 10; a[n_ /; n > 1 && Union[ IntegerDigits[n]] == {1}] := 9; Table[a[n], {n, 1, 76}] (* Jean-Fran├žois Alcover, Oct 24 2011 *)

Table[Function[r, SelectFirst[Range[2, 10^3], Length@ SequencePosition[ If[Depth@ # == 3, Flatten@ Join[#, Table[Last@ #, Length@ # + Length@ r]], PadRight[#, Length@ # + Length@ r]] &@ First@ RealDigits[1/#], r] > 0 &]]@ IntegerDigits@ n, {n, 120}] (* Michael De Vlieger, May 14 2016, Version 10.1 *)

CROSSREFS

Sequence in context: A154747 A217515 A079624 * A011097 A195475 A188725

Adjacent sequences:  A035332 A035333 A035334 * A035336 A035337 A035338

KEYWORD

easy,nice,nonn,base,look

AUTHOR

Erich Friedman

STATUS

approved

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Last modified February 23 02:43 EST 2018. Contains 299473 sequences. (Running on oeis4.)