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A sequence produced by sorting the digits of a number and adding them to the previous number. The algorithm terminates when a
sorted number is obtained. 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, ... (Sloane's A033862). The first few numbers not known to terminate are 316, 452, 697, 1376,
2743, 5090, ... (Sloane's A033861). The least numbers of sort-then-add persistence , 2, ..., are 1, 10, 65, 64, 175,
98, 240, 325, 302, 387, 198, 180, 550, ... (Sloane's A033863).
See also 196-Algorithm, RATS Sequence
References
Sloane, N. J. A. Sequences
A033861,
A033862, and
A033863
in ``An On-Line Version of the Encyclopedia of Integer Sequences.''
http://www.research.att.com/~njas/sequences/eisonline.html.