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A157784 as a simple table

na(n)
01
11
2-1
34
4-5
51
664
7-84
821
9-1
104096
11-5440
121428
13-85
141
151048576
16-1396736
17371008
18-23188
19341
20-1
211073741824
22-1431306240
23381308928
24-24115520
25372372
26-1365
271
284398046511104
29-5863704100864
301563272675328
31-99158478848

[1,1,-1,4,-5,1,64,-84,21,-1,4096,-5440,1428,-85,1,
 1048576,-1396736,371008,-23188,341,-1,1073741824,
 -1431306240,381308928,-24115520,372372,-1365,1,
 4398046511104,-5863704100864,1563272675328,
 -99158478848]