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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 56 |
| 4 | 287 |
| 5 | 1564 |
| 6 | 8896 |
| 7 | 52217 |
| 8 | 313955 |
| 9 | 1923775 |
| 10 | 11970066 |
| 11 | 75427608 |
| 12 | 480365740 |
| 13 | 3086989128 |
| 14 | 19992893796 |
| 15 | 130363352003 |
| 16 | 855099212950 |
| 17 | 5638480905533 |
| 18 | 37354602517624 |
| 19 | 248515024509486 |
| 20 | 1659620048332369 |
| 21 | 11121368629141886 |
| 22 | 74759777174598964 |
[1,3,12,56,287,1564,8896,52217,313955,1923775, 11970066,75427608,480365740,3086989128, 19992893796,130363352003,855099212950, 5638480905533,37354602517624,248515024509486, 1659620048332369,11121368629141886, 74759777174598964] |