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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 55 |
| 2 | 9217 |
| 3 | 280483 |
| 4 | 3378745 |
| 5 | 23803711 |
| 6 | 118513705 |
| 7 | 462945547 |
| 8 | 1512003793 |
| 9 | 4303999495 |
| 10 | 10987654321 |
| 11 | 25678050355 |
| 12 | 55776799177 |
| 13 | 113924725903 |
| 14 | 220792014745 |
| 15 | 408951042331 |
| 16 | 728121033505 |
| 17 | 1252121211607 |
| 18 | 2087920281313 |
[1,55,9217,280483,3378745,23803711,118513705, 462945547,1512003793,4303999495,10987654321, 25678050355,55776799177,113924725903,220792014745, 408951042331,728121033505,1252121211607, 2087920281313] |