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A172164 as a simple table

na(n)
220
319
420
519
620
721
818
921
1019
1120
1220
1320
1419
1520
1620
1719
1820
1920
2020
2119
2221
2318
2421
2519
2621
2718
2821
2919
3021
3118
3221
3319
3420
3520
3620
3719
3820
3920
4019
4120
4220
4320
4419
4520
4620
4720
4819
4921
5018
5121
5219
5320
5420
5520
5619
5720
5820
5920
6019
6120
6220
6319
6420
6520
6620
6719
6821
6918
7021

[20,19,20,19,20,21,18,21,19,20,20,20,19,20,20,19,
 20,20,20,19,21,18,21,19,21,18,21,19,21,18,21,19,
 20,20,20,19,20,20,19,20,20,20,19,20,20,20,19,21,
 18,21,19,20,20,20,19,20,20,20,19,20,20,19,20,20,
 20,19,21,18,21]