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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 87 |
| 4 | 530 |
| 5 | 3329 |
| 6 | 21316 |
| 7 | 138345 |
| 8 | 906853 |
| 9 | 5989967 |
| 10 | 39804817 |
| 11 | 265812731 |
| 12 | 1782288408 |
| 13 | 11991201709 |
| 14 | 80911836411 |
| 15 | 547334588037 |
| 16 | 3710610424765 |
| 17 | 25204313298581 |
| 18 | 171492983631249 |
| 19 | 1168638213247713 |
| 20 | 7974592724571446 |
| 21 | 54484621312318007 |
| 22 | 372671912259214487 |
[1,3,15,87,530,3329,21316,138345,906853,5989967, 39804817,265812731,1782288408,11991201709, 80911836411,547334588037,3710610424765, 25204313298581,171492983631249,1168638213247713, 7974592724571446,54484621312318007, 372671912259214487] |