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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 56 |
| 4 | 287 |
| 5 | 1564 |
| 6 | 8895 |
| 7 | 52195 |
| 8 | 313655 |
| 9 | 1920489 |
| 10 | 11938271 |
| 11 | 75143016 |
| 12 | 477948051 |
| 13 | 3067190311 |
| 14 | 19835032603 |
| 15 | 129129612163 |
| 16 | 845603794947 |
| 17 | 5566269982581 |
| 18 | 36810651063798 |
| 19 | 244448822313138 |
| 20 | 1629413356387998 |
| 21 | 10898124891668031 |
| 22 | 73116947514706451 |
[1,3,12,56,287,1564,8895,52195,313655,1920489, 11938271,75143016,477948051,3067190311, 19835032603,129129612163,845603794947, 5566269982581,36810651063798,244448822313138, 1629413356387998,10898124891668031, 73116947514706451] |