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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 30 |
| 4 | 154 |
| 5 | 1078 |
| 6 | 7046 |
| 7 | 50766 |
| 8 | 364268 |
| 9 | 2713444 |
| 10 | 20384884 |
| 11 | 155954760 |
| 12 | 1204192106 |
| 13 | 9400024042 |
| 14 | 73945396990 |
| 15 | 586088682472 |
| 16 | 4673927031694 |
| 17 | 37484566094970 |
| 18 | 302098932029282 |
| 19 | 2445538771089012 |
| 20 | 19875632898821430 |
| 21 | 162118004651048048 |
| 22 | 1326658157736876148 |
[1,2,4,30,154,1078,7046,50766,364268,2713444, 20384884,155954760,1204192106,9400024042, 73945396990,586088682472,4673927031694, 37484566094970,302098932029282,2445538771089012, 19875632898821430,162118004651048048, 1326658157736876148] |