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A066338 as a simple table

na(n)
00
11
22
33
44
58
69
710
811
912
1013
1114
1215
13-1
14-1
15-1
1616
1717
1818
1919
2020
2124
2225
2326
2427
2528
2629
2730
2831
29-1
30-1
31-1
3232
3333
3434
3535
3636
3740
3841
3942
4043
4144
4245
4346
4447
45-1
46-1
47-1
4848
4949
5050
5151
5252
5356
5457
5558
5659
5760
5861
5962
6063
61-1
62-1
63-1
6464
6565
6666
6767
6868
6972
7073
7174
7275
7376
7477
7578
7679
77-1
78-1
79-1
8080
8181
8282
8383
8484
8588
8689

[0,1,2,3,4,8,9,10,11,12,13,14,15,-1,-1,-1,16,17,
 18,19,20,24,25,26,27,28,29,30,31,-1,-1,-1,32,33,
 34,35,36,40,41,42,43,44,45,46,47,-1,-1,-1,48,49,
 50,51,52,56,57,58,59,60,61,62,63,-1,-1,-1,64,65,
 66,67,68,72,73,74,75,76,77,78,79,-1,-1,-1,80,81,
 82,83,84,88,89]