a(n)+a(n+1) = concatenation of n and (n+1)

 

Hello SeqFans,

 

start S with a(1) = 1 then :

 

n = 1....2....3....4....5....6....7....8....9....10...11...12...13...14

S = 1, 11, 12, 22, 23, 33, 34, 44, 45, 865,...

 

Ex:

1+11=12 which is 1 concatenated to 2

11+12=23 which is 2 concatenated to 3

12+22=34 which is 3 concatenated to 4

22+23=45 which is 4 concatenated to 5

etc.

 

The leftmost column is S.

Best,

.

 

-----------

 

Neil Sloane:

 

> Nice ! See http://oeis.org/A215027

 

Hans Havermann:

 

> Understandably, fractal-like shifts occur at powers of 10:

 

 

s200detail

 

 

s200

 

 

s2000

 

 

Thank you, Neil and Hans!

Best,

.