OFFSET
1,1
COMMENTS
Base 3 analog of A075252 (base 2), A075421 (base 4) and A063048 (base 10); subsequence of A077404. - A proof that the base 3 trajectory does not contain a palindrome has been found up to now for none of the terms. - If the trajectory of an integer k joins the trajectory of a smaller integer which is a term of the present sequence, then this occurs after very few Reverse and Add! steps (at most 9 for k < 20000). On the other hand, the trajectories of the terms of this sequence do not join the trajectory of any smaller term within at least 1000 steps.
LINKS
EXAMPLE
805 is a term since the trajectory of 805 (presumably) does not lead to a number which occurs in the trajectory of 103 or of 746.
MATHEMATICA
limit = 10^3; (* Assumes that there is no palindrome if none is found before "limit" iterations *)
utraj = {};
Select[Range[0, 21000], (i = 0;
x = NestWhileList[(i++; # + IntegerReverse[#, 3]) &, #, # !=
IntegerReverse[#, 3] && i < limit &];
If[i >= limit && Intersection[x, utraj] == {},
utraj = Union[utraj, x]; True,
utraj = Union[utraj, x]]) &]
(* Robert Price, Oct 19 2019 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Klaus Brockhaus, Nov 05 2002
EXTENSIONS
Offset changed to 1 by A.H.M. Smeets, Feb 14 2019
a(41)-a(48) from A.H.M. Smeets, Feb 18 2019
STATUS
approved