The sort-then-add sequence is produced by sorting the decimal digits of a positive
integer in nondecreasing order and adding the resulting integer
to the original number. Leading zeros in the sorted digit string are discarded when it is interpreted as an integer.
The values starting with 
, 2, ... are 2, 4, 6, 8, 10, 12, 14, 16, 18, 11, 22, 24,
... (OEIS A070196).
A starter is already sorted if its decimal digits are in nondecreasing order. The sorting-then-adding algorithm
stops as soon as a sorted number is obtained, including before any addition if the
starter is already sorted. Then for 
, 2, ..., the algorithm terminates on 1, 2, 3, 4, 5, 6, 7,
8, 9, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 33, ... (OEIS A033862).
The orbit starting at 316 begins 316, 452, 697, 1376, 2743, 5090, ... (OEIS A033861).
No sorted term is known in this orbit. The sort-then-add persistence of a terminating
starter is the number of additions required to reach its first sorted term. The least
numbers of sort-then-add persistence 
, 1, ..., are 1, 10, 65, 64, 175, 98, 240, 325, 302, 387,
198, 180, 550, ... (OEIS A033863).
