Le dernier chiffre plus 1
Hello Seqfans,
This was fun to
imagine:
Start S with a(n)=1
Now a(n+1) is always the smallest integer not yet present in S such
that a(n+1) is a multiple of (d+1), d being
the last digit of a(n):
S=1,2,3,4,5,6,7,8,9,10,11,12,15,18,27,16,14,20,13,24,25,30,17,32,21,...
S is a permutation of N(aturals),
I hope (it was imagined with this
purpose in mind).
Example:
2 is the smallest integer not yet in S that is a multiple of (1+1)
3 is the smallest integer not yet in S that is a multiple of (2+1)
4 is the smallest integer not yet in S that is a multiple of (3+1)
...
10 is the smallest
integer not yet in S that is a
multiple of (9+1)
11 is the smallest
integer not yet in S that is a multiple
of (0+1)
12 is the smallest
integer not yet in S that is a
multiple of (1+1)
15 is the smallest
integer not yet in S that is a
multiple of (2+1)
18 is the smallest
integer not yet in S that is a
multiple of (5+1)
27 is the smallest
integer not yet in S that is a
multiple of (8+1)
16 is the smallest
integer not yet in S that is a
multiple of (7+1)
...

This is d, the last
digit of a(n) +
I’d like to see the
graph of S... Any taker?
Best,
É.
__________
Emmanuel Vantieghem was
quick to answer:
> Concerns : your mail to the SeqFans
of 4/12/2013
> Attached : a small plot of the first 1024
elements of S
Many thanks, Emmanuel!
Best,
É.