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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 44 |
| 4 | 225 |
| 5 | 1182 |
| 6 | 6321 |
| 7 | 34232 |
| 8 | 187137 |
| 9 | 1030490 |
| 10 | 5707449 |
| 11 | 31760676 |
| 12 | 177435297 |
| 13 | 994551222 |
| 14 | 5590402785 |
| 15 | 31500824304 |
| 16 | 177880832001 |
| 17 | 1006362234162 |
| 18 | 5703029112297 |
| 19 | 32367243171740 |
| 20 | 183945502869345 |
| 21 | 1046646207221582 |
| 22 | 5961966567317649 |
| 23 | 33995080211156904 |
[1,2,9,44,225,1182,6321,34232,187137,1030490, 5707449,31760676,177435297,994551222,5590402785, 31500824304,177880832001,1006362234162, 5703029112297,32367243171740,183945502869345, 1046646207221582,5961966567317649, 33995080211156904] |