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A231898 as a simple table

na(n)
1-1
2-1
32
4-1
54
63
74
83
94
105
115
125
136
145
155
165
176
186
196
206
216
226
236
246
256
266

[-1,-1,2,-1,4,3,4,3,4,5,5,5,6,5,5,5,6,6,6,6,6,6,6,
 6,6,6]