Add-and-reverse: A007396,A003608,A007397,A007398,A007399

[Joshua Zucker]

For n = 65 it appears also not to cycle (at least after half a million
terms, there's no cycle).

n = 115 also.

And of course all the multiples of 10, though I lack the patience
today to get that out to half a million terms (I wrote a very slow
program; it could easily be sped up a lot; right now I use infinite
precision integers, add the number, convert to string, convert to
array (list, in Scheme), and reverse the list, convert back to string,
and then back to number.)

By the way, if you're working on the equilateral triangle in lattice
cube of side n,
a(7) = 16176.

--Joshua Zucker



On Sat, 5 Feb 2005 22:22:40 +0200, זקיר סעידוב - ד\"ר/Zakir Seidov 
Ph.D. <zakirs at yosh.ac.il> wrote:
>  
> 
> Dear seqfans, 
> 
> In A007396, A003608, A007397, A007398, A007399, 
> 
> the "add m and reverse!" rule is considered for m = 2, 4, 5, 7, 8, 
> respectively. 
> 
> As usually, in such cases, SEQ may end with cycle, or not. 
> 
> I checked all cases for m 1 to 30, and found that cycles occur 
> 
> in all cases, except m = 10,20,30 
> 
> (actually I've checked some (1-3)10^5 terms, with no cycle). 
> 
> Can anyone find the cycle or prove that no cycle exists in m = 10,20,30...
> cases. 
> 
> Thanks, 
> 
> Zak 
> 
> Neil, 
> 
> Are these 30 SEQs OK for OEIS?