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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 29 |
| 4 | 120 |
| 5 | 820 |
| 6 | 3625 |
| 7 | 23400 |
| 8 | 105000 |
| 9 | 669500 |
| 10 | 3075625 |
| 11 | 18837500 |
| 12 | 89237500 |
| 13 | 532500000 |
| 14 | 2554062500 |
| 15 | 15086640625 |
| 16 | 72843750000 |
| 17 | 421773437500 |
| 18 | 2084812500000 |
| 19 | 11834804687500 |
| 20 | 58638281250000 |
| 21 | 332210205078125 |
| 22 | 1656773437500000 |
| 23 | 9240966796875000 |
| 24 | 46624682617187500 |
| 25 | 257479980468750000 |
[1,1,4,29,120,820,3625,23400,105000,669500, 3075625,18837500,89237500,532500000,2554062500, 15086640625,72843750000,421773437500, 2084812500000,11834804687500,58638281250000, 332210205078125,1656773437500000,9240966796875000, 46624682617187500,257479980468750000] |