[seqfan] Colorless integers

[Eric Angelini]

Hello SeqFans,

(I hope this is not old hat)

Let N be an integer
Let S be the sum of N's digits
--> make M=N+S if S is even
--> make M=N-S if S is odd
Iterate.

Example:

71(+8)=79
       79(+16)=95
               95(+14)=109
                       109(+10)=119
                                119(-11)=108
                                         108(-9)=99
                                                 99(+18)=117
                                                         117(-9)=108
Thus 71 enters in the loop 99.117.108.99

(sequitur here:
http://www.cetteadressecomportecinquantesignes.com/Colorless.htm)

Best,
É.