A070023 - OEIS

%I #8 Jun 12 2022 02:58:38

%S 1,2,3,4,5,6,8,9,10,12,15,16,18,20,24,25,30,32,36,40,45,48,50,60,64,

%T 72,75,80,90,96,100,120,125,128,144,150,160,180,192,200,225,240,250,

%U 256,288,300,320,360,375,384,400,450,480,500,512,576,600,625,640,720,750

%N 1/n has period 1 in base 10 (including terminating decimals).

%F a(n) = A070022(n)/11. Numbers of the form a*b*c where a is in {1, 3, 9}, b is a power of 2 and c is a power of 5.

%e 12 is in the sequence since 1/12 = 0.08333333333...

%e 11 is not since 1/11 = 0.0909090909...

%e 10 is in, since 1/10 = 0.1000000... = 0.099999999...

%t Select[Range[750], Length[RealDigits[1/#][[1, -1]]] <= 1 &] (* _Amiram Eldar_, Jun 12 2022 *)

%Y Cf. A003592, A069105, A070021, A070022.

%K base,nonn

%O 1,2

%A _Henry Bottomley_, Apr 12 2002