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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 40 |
| 5 | 205 |
| 6 | 276 |
| 7 | 1939 |
| 8 | 4432 |
| 9 | 13689 |
| 10 | 18100 |
| 11 | 199111 |
| 12 | 200784 |
| 13 | 2610205 |
| 14 | 3136420 |
| 15 | 3191595 |
| 16 | 7012576 |
| 17 | 119213809 |
| 18 | 137103012 |
| 19 | 2604957247 |
| 20 | 2605199080 |
| 21 | 2608367181 |
| 22 | 3084857644 |
| 23 | 70951725835 |
| 24 | 71062911792 |
| 25 | 355315542025 |
| 26 | 442803520276 |
[1,4,15,40,205,276,1939,4432,13689,18100,199111, 200784,2610205,3136420,3191595,7012576,119213809, 137103012,2604957247,2605199080,2608367181, 3084857644,70951725835,71062911792,355315542025, 442803520276] |