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A124646 as a simple table

na(n)
1-1
2-2
3-10
4-37
5-143
6-478
7-1588
8-4910
9-14748
10-42235
11-116910
12-311478
13-803343
14-2004434
15-4853669
16-11414943
17-26127222
18-58267164
19-126811068
20-269647980
21-560935635
22-1142812869
23-2282784640
24-4475122564

[-1,-2,-10,-37,-143,-478,-1588,-4910,-14748,
 -42235,-116910,-311478,-803343,-2004434,-4853669,
 -11414943,-26127222,-58267164,-126811068,
 -269647980,-560935635,-1142812869,-2282784640,
 -4475122564]