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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 6 |
| 4 | 32 |
| 5 | 250 |
| 6 | 2592 |
| 7 | 33614 |
| 8 | 524288 |
| 9 | 9565938 |
| 10 | 200000000 |
| 11 | 4715895382 |
| 12 | 123834728448 |
| 13 | 3584320788074 |
| 14 | 113387824750592 |
| 15 | 3892390136718750 |
| 16 | 144115188075855872 |
| 17 | 5724846103019631586 |
| 18 | 242879062193188503552 |
[2,2,6,32,250,2592,33614,524288,9565938,200000000, 4715895382,123834728448,3584320788074, 113387824750592,3892390136718750, 144115188075855872,5724846103019631586, 242879062193188503552] |