[seqfan] Re: Concatenate the sums of the neighboring digits

[Hans Havermann]

Note that whenever three or more 9s find themselves adjacent inside a number, these segments will reproduce every second generation and grow. Continuing your 5677 example:

...
786337
15149610
665131571
12116446128
3327108107310
6598189171041
11141799171088145
22558161810881816959
4710139779918169997151414

The last one has three adjacent 9s so the sequence will grow forever.