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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 166 |
| 5 | 1806 |
| 6 | 20382 |
| 7 | 272706 |
| 8 | 8323326 |
| 9 | 158143194 |
| 10 | 4319806194 |
| 11 | 139715547110 |
| 12 | 4563596609414 |
| 13 | 154716297384250 |
| 14 | 6051527318503338 |
| 15 | 315946019303255670 |
| 16 | 18477283150919171654 |
| 17 | 1191953715632050834242 |
| 18 | 76457609628854745786262 |
| 19 | 4838004466153152832995822 |
| 20 | 312401901306255000752991994 |
| 21 | 20039165126917559409941672886 |
[1,2,6,18,166,1806,20382,272706,8323326,158143194, 4319806194,139715547110,4563596609414, 154716297384250,6051527318503338, 315946019303255670,18477283150919171654, 1191953715632050834242,76457609628854745786262, 4838004466153152832995822, 312401901306255000752991994, 20039165126917559409941672886] |