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A119396
Numbers n such that A086793(n)=20.
3
924, 1104, 1134, 1540, 1650, 1760, 1820, 1908, 1992, 2016, 2288, 2556, 2632, 2744, 2860, 2940, 2970, 3000, 3192, 3204, 3220, 3248, 3400, 3630, 3738, 3784, 3840, 3852, 3880, 3968, 3990, 4134, 4260, 4410, 4464, 4674, 4736, 4860, 4875, 4930, 4992, 5016
OFFSET
1,1
COMMENTS
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.
LINKS
EXAMPLE
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.
MAPLE
f:= proc(n) option remember; local t;
if kernelopts(level) > 460 then return FAIL fi;
t:= add(convert(convert(d, base, 10), `+`), d=numtheory:-divisors(n));
1+procname(t)
end proc:
f(15):= 0:
f(1):= FAIL:
Res:= NULL: count:= 0:
for n from 1 while count < 100 do
if f(n) = 20 then
count:= count+1;
Res:= Res, n;
fi
od:
Res; # Robert Israel, Apr 03 2018
KEYWORD
base,nonn
AUTHOR
Zak Seidov, May 17 2006
EXTENSIONS
Edited by Robert Israel, Apr 03 2018
STATUS
approved