VOOZH about

URL: https://oeis.org/A070021

⇱ A070021 - OEIS

login
A070021
1/n has period 1 in base 10 (but not terminating).
6
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
KEYWORD
nonn,base,easy
AUTHOR
Henry Bottomley, Apr 12 2002
STATUS
approved