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A001670 as a simple table

na(n)
12
22
34
44
54
64
76
86
96
106
116
126
138
148
158
168
178
188
198
208
2110
2210
2310
2410
2510
2610
2710
2810
2910
3010
3112
3212
3312
3412
3512
3612
3712
3812
3912
4012
4112
4212
4314
4414
4514
4614
4714
4814
4914
5014
5114
5214
5314
5414
5514
5614
5716
5816
5916
6016
6116
6216
6316
6416
6516
6616
6716
6816
6916
7016

[2,2,4,4,4,4,6,6,6,6,6,6,8,8,8,8,8,8,8,8,10,10,10,
 10,10,10,10,10,10,10,12,12,12,12,12,12,12,12,12,
 12,12,12,14,14,14,14,14,14,14,14,14,14,14,14,14,
 14,16,16,16,16,16,16,16,16,16,16,16,16,16,16]