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Numbers n such that A086793(n)=20.
3

%I #16 Apr 04 2018 15:44:06

%S 924,1104,1134,1540,1650,1760,1820,1908,1992,2016,2288,2556,2632,2744,

%T 2860,2940,2970,3000,3192,3204,3220,3248,3400,3630,3738,3784,3840,

%U 3852,3880,3968,3990,4134,4260,4410,4464,4674,4736,4860,4875,4930,4992,5016

%N Numbers n such that A086793(n)=20.

%C Some trajectories are: 924,168,102,36,46,18,30,27,22,9,13,5,6,12,19,11,3,4,7,8,15 1104,168,102,... 1540,162,66,36,... 1650,162,66,36,... 2016,297,66,36,... 2940,297,66,36,... 3192,312,102,36,... All trajectories eventually join one of previous trajectories.

%H Robert Israel, <a href="/A119396/b119396.txt">Table of n, a(n) for n = 1..10000</a>

%e 924 is a term because it reaches 15 in 20 steps with this trajectory 924,168,102,36,46,18,30,27,22,9,13,5,6,12,19,11,3,4,7,8,15.

%p f:= proc(n) option remember; local t;

%p if kernelopts(level) > 460 then return FAIL fi;

%p t:= add(convert(convert(d,base,10),`+`),d=numtheory:-divisors(n));

%p 1+procname(t)

%p end proc:

%p f(15):= 0:

%p f(1):= FAIL:

%p Res:= NULL: count:= 0:

%p for n from 1 while count < 100 do

%p if f(n) = 20 then

%p count:= count+1;

%p Res:= Res, n;

%p fi

%p od:

%p Res; # _Robert Israel_, Apr 03 2018

%Y Cf. A034690, A086793, A094501, A095347, A114527, A118358, A119397, A119398, A260059.

%K base,nonn

%O 1,1

%A _Zak Seidov_, May 17 2006

%E Edited by _Robert Israel_, Apr 03 2018