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A101980 as a simple table

na(n)
00
11
20
3-1
44
50
64
7-9
89
90
10-33
1164
12-36
1316
140
15456
16-825
17400
18-100
1925
200
21-9460
2216416
23-7425
241600
25-225
2636
270
28274800
29-463540
30201096
31-40425
324900
33-441
3449
350
36-10643745
3717587200
38-7416640
391430016
40-161700
4112544
42-784
4364
440
45530052880
46-862143345
47356140800
48-66749760
497239456

[0,1,0,-1,4,0,4,-9,9,0,-33,64,-36,16,0,456,-825,
 400,-100,25,0,-9460,16416,-7425,1600,-225,36,0,
 274800,-463540,201096,-40425,4900,-441,49,0,
 -10643745,17587200,-7416640,1430016,-161700,12544,
 -784,64,0,530052880,-862143345,356140800,
 -66749760,7239456]