A365368 - OEIS

%I #4 Sep 03 2023 10:41:38

%S 5,5,5,20,10245,10,20,10245,15,130,30,20,10245,105,25,45,130,30,245,

%T 55,35,10245,105,40,70,120,45,130,80,50,145,245,55,95,270,60,10245,

%U 105,65,520,870,70,120,2605,75,355,130,80,380,230,85,145,245,90,255,155,95

%N First integer > n reached under iteration of map x -> (5/3)*round(x) when started at n, or -1 if no such integer is ever reached.

%C Conjecture: an integer will always be reached, i.e. a(n) > 0 for all n.

%o (Python)

%o from fractions import Fraction

%o def A365368(n):

%o     x = Fraction(n)

%o     while x.denominator > 1 or x<=n:

%o         x = Fraction(5*x.__round__(),3)

%o     return int(x)

%Y Cf. A087704, A087705, A087706, A087707, A087708, A087709, A365341, A365342, A365367.

%K nonn

%O 1,1

%A _Chai Wah Wu_, Sep 02 2023