A104989 - OEIS

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A104989 as a simple table

n	a(n)
0	1
1	3
2	13
3	69
4	433
5	3133
6	25657
7	234537
8	2367825
9	26176981
10	314670353
11	4088360569
12	57112939433
13	853922061413
14	13609089281849
15	230346936181465
16	4127180489763649
17	78046835384582069
18	1553536327234953153

[1,3,13,69,433,3133,25657,234537,2367825,26176981, 314670353,4088360569,57112939433,853922061413, 13609089281849,230346936181465,4127180489763649, 78046835384582069,1553536327234953153]