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
Robert Israel, Table of n, a(n) for n = 1..10000
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
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Zak Seidov, May 17 2006
EXTENSIONS
Edited by Robert Israel, Apr 03 2018
STATUS
approved