A070021 1/n has period 1 in base 10 (but not terminating).

3, 6, 9, 12, 15, 18, 24, 30, 36, 45, 48, 60, 72, 75, 90, 96, 120, 144, 150, 180, 192, 225, 240, 288, 300, 360, 375, 384, 450, 480, 576, 600, 720, 750, 768, 900, 960, 1125, 1152, 1200, 1440, 1500, 1536, 1800, 1875, 1920, 2250, 2304, 2400, 2880, 3000, 3072, 3600

Offset

1,1

Links

Michael De Vlieger, Table of n, a(n) for n = 1..11778 (a(n) < 10^50)

Formula

Numbers of the form a*b*c where a is in {3, 9}, b is a power of 2 and c is a power of 5.

Example

12 is in the sequence since 1/12=0.08333333333...; 11 is not since 1/11=0.0909090909...; 10 is not, since despite 1/10=0.099999999..., it is also true that 1/10=0.1 exactly.

Mathematica

mx = 5000; Select[ Union@ Flatten@ Table[2^t*5^f {3, 9}, {t, 0, Log[2, mx/3]}, {f, 0, Log[5, mx/(2^t*3)]}], # < mx &] (* Robert G. Wilson v, Apr 27 2017 *)

Crossrefs

Cf. A003592, A069105, A070022, A070023.

Sequence in context: A193803 A284601 A039004 * A083354 A156242 A060293

Adjacent sequences: A070018 A070019 A070020 * A070022 A070023 A070024

Keyword

nonn,base,easy

Author

Henry Bottomley, Apr 12 2002

Status

approved